Nanomaterials, Polymers and Devices E-Book
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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Providing an eclectic snapshot of the current state of the art and future implications of the field, Nanomaterials, Polymers, and Devices: Materials Functionalization and Device Fabrication presents topics grouped into three categorical focuses: * The synthesis, mechanism and functionalization of nanomaterials, such as carbon nanotubes, graphene, silica, and quantum dots * Various functional devices which properties and structures are tailored with emphasis on nanofabrication. Among discussed are light emitting diodes, nanophotonic, nano-optical, and photovoltaic devices * Nanoelectronic devices, which include semiconductor, nanotube and nanowire-based electronics, single-walled carbon-nanotube based nanoelectronics, as well as thin-film transistors
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Seitenzahl: 1753
Veröffentlichungsjahr: 2015
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Table of Contents
Cover
Title Page
Copyright
Contributors
Foreword
Chapter 1: THE FUNCTIONALIZATION OF CARBON NANOTUBES AND NANO-ONIONS
1.1 Functionalization of Carbon Nanotubes
1.2 Functionalization of Carbon Nano-Onions
1.3 Conclusions and Future Scope
References
Chapter 2: THE FUNCTIONALIZATION OF GRAPHENE AND ITS ASSEMBLED MACROSTRUCTURES
2.1 Introduction
2.2 Noncovalent Functionalization
2.3 Covalent Functionalization
2.4 Macroscopic Assembled Graphene Fibers, Films, and Foams
2.5 Conclusions and Future Scope
References
Chapter 3: DEVICES BASED ON GRAPHENE AND GRAPHANE
3.1 Graphene, A Groundbreaking Material
3.2 Beyond Graphene: Graphane, A Two-Dimensional Hydrocarbon
3.3 Graphene and Graphane Analogues
3.4 Conclusion Remarks
Acknowledgment
References
Chapter 4: LARGE-AREA GRAPHENE AND CARBON NANOSHEETS FOR ORGANIC ELECTRONICS: SYNTHESIS AND GROWTH MECHANISM
4.1 Introduction
4.2 Graphene Grown on Metal Catalysts
4.3 Direct Synthesis of Graphene on Affordable Substrates
4.4 Carbon Nanosheets Similar to Graphene
4.5 Summary
Acknowledgment
References
Chapter 5: Functionalization of Silica Nanoparticles for Corrosion Prevention of Underlying Metal
5.1 Intorduction
5.2 Silica Particles for Corrosion Prevention
5.3 Corrosion Resistant Silicone Conformal Coating Preparation and Testing
5.4 Conclusion
Experimental Procedure
References
Chapter 6: NEW NANOSCALE MATERIAL: GRAPHENE QUANTUM DOTS
6.1 Introduction
6.2 Classification of Synthetic Methods of GQDs
6.3 Surface Functionalization and Congregation of GQDs
6.4 Physical Properties of GQDs
6.5 Applications
6.6 Perspectives
References
Chapter 7: Recent Progress of Iridium(III) Red Phosphors for Phosphorescent Organic Light-Emitting Diodes
7.1 Introduction
7.2 Iridium(III) Red Dopants Containing Various Cyclometalated Ligands
7.3 Conclusion
Acknowledgments
References
Chapter 8: Four-Wave Mixing and Carrier Nonlinearities in Graphene–Silicon Photonic Crystal Cavities
8.1 Kerr Nonlinearities in Graphene–Silicon Photonic Crystal Cavities
8.2 Effective Kerr Nonlinearities in Graphene–Silicon System
8.3 Device Fabrication and Calibration
8.4 Four-Wave Mixing in Photonic Crystal Cavity
8.5 Free-Carrier Dynamics in Graphene–Silicon Photonic Crystal Cavities
8.6 Graphene Thermal and Free-Carrier Nonlinearities
8.7 Conclusions
References
Chapter 9: Polymer Photonic Devices
9.1 Introduction
9.2 Technology Overview for Polymer Photonic Device Fabrication
9.3 Passive Polymer Photonic Devices
9.4 Thermally Tunable Polymer Photonic Devices
9.5 Hybrid Photonic Integration on Polymer Platform
9.6 Reliability Test
References
Chapter 10: Low Dielectric Contrast Photonic Crystals
10.1 Introduction
10.2 Photonic Crystals
10.3 Cavities and Resonators
10.4 Resonators in Periodic Ridge Waveguides
10.5 Omnidirectional Photonic Bandgap
10.6 Microcavities in Two-Dimensional Low Index Photonic Crystals
10.7 Conclusion
References
Chapter 11: Microring Resonator Arrays for Sensing Applications
11.1 Basic Properties of Microring Resonators
11.2 Technology of Microring Resonators
11.3 Sensor Arrays for Multiplexed Detection/MULTIPARAMETER Analysis
11.4 Multiplexing by Modulation of Individual MRRS
11.5 Experimental Demonstration of the Modulation Scheme
11.6 System Integration and Economical Solutions for Optical Sources
11.7 Perspectives
References
Chapter 12: Polymers, Nanomaterials, and Organic Photovoltaic Devices
12.1 Polymer Solar Cells
12.2 Materials for Polymer Solar Cells
12.3 Polymer Solar Cell Processing
12.4 Polymer Solar Cell Stability
12.5 Present State of Polymer Solar Cells and Perspectives
References
Chapter 13: Next-Generation GA Photovoltaics
13.1 Introduction
13.2 Optical and Electrical Properties of GA Planar Solar Cells
13.3 Optical and Electrical Properties of GA Nanopillar Solar Cells
13.4 Advanced Topics for High-Efficiency Nanopillar Photovoltaics
13.5 Conclusions and Future Directions
References
Chapter 14: Nanocrystals, Layer-by-Layer Assembly, and Photovoltaic Devices
14.1 Introduction
14.2 Nucleation and Growth of Colloidal Nanocrystals
14.3 Layer-by-Layer Assembly of Sintered Nanocrystal Thin Films
14.4 Sintered Nanocrystal Solar Cells Using LL Assembly
14.5 Conclusions
References
Chapter 15: Nanostructured Conductors for Flexible Electronics
15.1 Introduction
15.2 Transparent Electrodes
15.3 Stretchable Conductors
15.4 Pressure-Sensitive Films
15.5 Concluding Remarks
References
Chapter 16: Graphene, Nanotube, and NANOWIRE-Based Electronics
16.1 Graphene
16.2 Carbon Nanotube (CNT)
16.3 Nanowire
References
Chapter 17: NANOELECTRONICS BASED ON SINGLE-WALLED CARBON NANOTUBES
17.1 INTRODUCTION
17.2 ELECTRICAL PROPERTIES OF NANOTUBES AND DEVICE PHYSICS
17.3 MATERIALS AND PROCESSING
17.4 CIRCUIT- AND SYSTEM-LEVEL DEMONSTRATION OF NANOTUBE-BASED NANOELECTRONICS
17.5 SUMMARY AND PERSPECTIVE
References
Chapter 18: Monolithic Graphene–Graphite Integrated Electronics
18.1 Introduction
18.2 Graphene Synthesis and Applications
18.3 MONOLITHIC GRAPHENE–GRAPHITE INTEGRATED ELECTRONICS
18.4 Future Directions: Graphene Bioelectronics
References
Chapter 19: THIN-FILM TRANSISTORS BASED ON TRANSITION METAL DICHALCOGENIDES
19.1 INTRODUCTION
19.2 MATERIALS PROPERTIES OF MoS
2
19.3 PERFORMANCE OF MoS
2
THIN-FILM TRANSISTORS
19.4 ISSUES IN MoS
2
THIN-FILM TRANSISTORS
19.5 CONCLUSION
References
Index
End User License Agreement
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Guide
Cover
Table of Contents
Foreword
Begin Reading
List of Illustrations
Chapter 1: THE FUNCTIONALIZATION OF CARBON NANOTUBES AND NANO-ONIONS
Figure 1.1 Model structures of carbon: (a) diamond, (b) fullerene, (c) multilayer fullerene, (d) single-walled carbon nanotubes, (e) double-walled carbon nanotubes, (f) multiwalled carbon nanotubes, and (g) graphene. (Reproduced with permission from Reference (2)).
Figure 1.2 Synthetic strategy for grafting linear glycopolymer from surfaces of MWNTs by ATRP. (Reproduced with permission from Reference (23)).
Figure 1.3 Schematic illustration of (a) CNTs dispersed mechanically in polymer matrix, (b) polymer-bonded CNTs, (c) polymer-coated CNTs by layer-by-layer self-assembly approach, and (d) polymer-functionalized CNTs dispersed in free polymer matrix. (
Source
: Reproduced with permission from Reference 39).
Figure 1.4 Schematic description of dendritic polymers. (
Source
: Reproduced with permission from Reference 51).
Figure 1.5 HP-grafted CNTs – branched-like trees. Graphical representation of a section of MWNTHP nanohybrids presented in this chapter (top) and a photograph of the trees grown on a hillside (bottom). (
Source
: Reproduced with permission from Reference 54).
Figure 1.6 TEM images of MWNT-HP5 at (a) low magnification and (b) high magnification. (
Source
: Reproduced with permission from Reference 54).
Figure 1.7 Complete functionalization strategy of ROP. (
Source
: Reproduced with permission from Reference 60).
Figure 1.8 Synthesis of dendritic HP-MWNT nanohybrid through
in situ
ROP. (
Source
: Reproduced with permission from Reference (54)).
Figure 1.9 Grafting of PCL onto MWNTs. (
Source
: Reproduced with permission from Reference 62).
Figure 1.10 Functionalization of multiwalled carbon nanotubes (MWCNTs) with hyperbranched polyglycerol (HPG) by anionic ring-opening polymerization (ROP) and modification of the grafted HPG. (
Source
: Reproduced with permission from Reference 65).
Figure 1.11 Chemical reactions on f-MWNTs. (
Source
: Reproduced with permission from Reference 66).
Figure 1.12 Synthetic strategy for grafting hyperbranched glycopolymer from surfaces of MWNTs by self-condensing vinyl copolymerization (SCVCP) of inimer (AB*) and monomer (M) via ATRP. (
Source
: Reproduced with permission from Reference 23).
Figure 1.13 Carbon nano-“onions” created by arc discharge in water. (a) Image of a carbon arc discharge in water. Scale bar, 12 mm. (b, c) Low- and high-magnification electron micrographs of carbon nano-onions floating on the water surface after their production. Scale bars, 10 nm. (
Source
: Reproduced with permission from Reference 95).
Figure 1.14 Reductive treatment of CNOs by a Na–K alloy in 1,2-DME and subsequent alkylation using 1-bromohexadecane. (
Source
: Reproduced with permission from Reference 97).
Chapter 2: THE FUNCTIONALIZATION OF GRAPHENE AND ITS ASSEMBLED MACROSTRUCTURES
Figure 2.1 A schematic depicting the synthesis of pyrene-terminated PNIPAAm using a pyrene-functional RAFT agent and the subsequent attachment of the polymer to graphene. (
Source
: Reproduced with permission from (19)).
Figure 2.2 (a) (Left) Photograph of a polymer PmPV/DCE solution with GNRs stably suspended in the solution. (Right) Schematic drawing of a graphene nanoribbon with two units of a PmPV polymer chain adsorbed on top of the graphene via π-stacking. (b) AFM images of selected GNRs with widths in the sub-10-nm regions.
Figure 2.3 (a) Photographs of GO/PVA mixtures with varied content ratio. (b) Photographs of the pH-induced gel–sol transition. (
Source
: Reproduced with permission from (23)).
Figure 2.4 Schematic showing synthesis of DNA-stabilized graphene aqueous suspensions and fabrication of lamellar multifunctional nanocomposites. (a) Oxidative treatment of graphite yield delaminated nanometer-thick sheets of GO. (b) Chemical reduction of GO sols with hydrazine in the presence of freshly prepared single-stranded DNA (ssDNA) produced a stable aqueous suspension of ssDNA-functionalised graphene sheets (ssDNA-G). (c,d) Processing of ssDNA-G dispersions to produce ordered layered nanocomposites; (c) evaporation induced deposition and self-assembly on flat substrates results in lamellar nanocomposite films with intercalated ssDNA molecules, and (d) co-assembly of negatively charged ssDNA-G sheets and positively charged cytochrome
c
produces co-intercalated multifunctional layered nanocomposites.
Figure 2.5 Structure models of lauryltrimethylammonium chloride-intercalated GOs with interlayer spacings of 1.2 nm (a), 1.6 nm (b), Ic = 1.9 nm (c), 2.9 nm (d).
Figure 2.6 Proposed structure of the copolymer coated graphene (a) and supramolecular well-dispersed graphene sheet containing hybrid hydrogel (b).
Figure 2.7 Chemically derived single-layer graphene sheets from the solution phase. (a) Schematic of the exfoliated graphite reintercalated with sulphuric acid molecules (small spheres) between the layers. (b) Schematic of tetrabutylammonium hydroxide (TBA, big spheres) insertion into the intercalated graphite. (c) Schematic of GS coated with DSPE-mPEG molecules and a photograph of a DSPE-mPEG/DMF solution of GS.
Figure 2.8 (a) Synthesis scheme of TPP-NHCO-SPFGraphene. (b) Schematic representation of part of the structure of the covalent TPP-NHCO-SPFGraphene. (
Source
: Reproduced with permission from (35)).
Figure 2.9 Synthesis procedure for benzoxazole- and benzimidazole-grafted graphene via heterocyclization reaction. (
Source
: Reproduced with permission from (39)).
Figure 2.10 Schematic illustration of the reaction employed for (a) functionalization of graphene oxide with cysteamine and (b) procedures for Hg
2+
determination. (
Source
: Reproduced with permission from (40)).
Figure 2.11 Synthesis of GO-TDI, DDAT-PVK, and GO-PVK. (
Source
: Reproduced with permission from (49)).
Figure 2.12 Reaction pathway involved in the functionalization of GO nanosheets with polymer chains. (
Source
: Reproduced with permission from (51)).
Figure 2.13 Synthesis route of polystyrene-functionalized graphene nanosheets. (
Source
: Reproduced with permission from (52)).
Figure 2.14 Schematic illustration of the three-step process for functionalization of graphene with PMMA by ATRP at room temperature. (
Source
: Reproduced with permission from (54)).
Figure 2.15 (a) In situ growing of PPEGEEMA polymer chains via SET-LRP from the surface of “TRIS” modified graphene oxide sheets. (b) Dispersion of TRIS-GO-PPEGEEMA in various solvents with a concentration of about 5.0 mg/ml. (
Source
: Reproduced with permission from (55)).
Figure 2.16 (a) Scheme of synthesizing 2D macromolecular brushes by free radical polymerization of various monomers with the backbone of GO sheets. The sheet represents GO, and the dots and double bonds represent radicals and active grafting points, respectively. (b) AFM height images of GO and GO-
g
-PGMA 2D brushes at different reaction time (size for all images: 1 µm × 1 µm). (
Source
: Reproduced with permission from (66)).
Figure 2.17 (a) Photographs of aqueous solutions of GO-PAA upon standing for 3 h at different pH values. (b) Schematic illustration of pH responsibility of GO-PAA. (c) Photographs of aqueous solution of GO-PNIPAM at (a) 25 °C for 3 h and (b) 35 °C for 10 min. (d) Schematic illustration of thermal responsibility of GO-PNIPAM. (
Source
: Reproduced with permission from (67)).
Figure 2.18 Scheme of synthesizing NG composites by in situ ring-opening polymerization of caprolactam in the presence of GO. The grey bonds in the nylon 6-grafted graphene represent restored conjugated bonds through high-temperature reduction; the curves represent the grafted PA6 macromolecular chains. (
Source
: Reproduced with permission from (70)).
Figure 2.19 Synthetic route of water-dispersible PG-
g
-GO nanostructure and its immobilization with B-
f
-MNPs. (
Source
: Reproduced with permission from (71)).
Figure 2.20 Macroscopic neat GO fibers and chemically reduced graphene fibers. (a) Four-meter-long GO fiber wound on a Teflon drum (diameter, 2 cm). (b) SEM image of the fiber. (c) The typical tighten knots of GO fibers. (d) The fracture morphology of GO fiber after tensile tests. The surface wrinkled morphology (e) and the tighten knot (f) of chemically reduced graphene fiber. (g) A Chinese character (“”, Zhong) pattern knitted in the cotton network (white) using two graphene fibers (black). (h) A mat of graphene fibers (horizontal) woven together with cotton threads (vertical). Scale bars, 50 µm (b–f) and 2 mm (g, h). (
Source
: Reproduced with permission from (72)).
Figure 2.21 A schematic depicting the synthesis of HPG/graphene hybrid fiber with brick-mortar structures by the wet spinning. (i) Synthesis of HPG-enveloped graphene sheets sandwich building blocks via reaction of GO and HPG at 160 °C for 18 □ h. (ii) Pre-alignment of HPG-enveloped graphene sheets in highly concentrated liquid crystalline spinning dope. (iii) Formation of hierarchically assembled continuous artificial nacre fibres via wet-spinning. (
Source
: Reproduced with permission from (76)).
Figure 2.22 (a) A digital photo of an ultrathin graphene nanofiltration membrane (uGNM). (b) Schematic representation of a base-refluxing reduced GO (bRGO). (c) Schematic view for possible permeation route: water molecules go through the nanochannels of the uGNMs and the holes on the graphene sheets and at last reach the pores of the supporting membranes. The blank squares present the holes on the graphene sheets (black line). The edges of the bRGO and the periphery of the holes are negatively charged. (
Source
: Reproduced with permission from (95)).
Figure 2.23 (a) A 100 cm
3
ultra-flyweight superelastic carbonaceous aerogel (UFA) cylinder standing on a flowerlike dog's tail (
Setaira viridis
(L.)
Beauv
). (b, c) The schematic model and
in situ
SEM observations of a single graphene@CNTs cell wall in the process of compressing and releasing shows the elastic mechanism of the UFA: the deformation of cell walls rather than the sliding between them. (d) Temperature dependence of the storage modulus (light grey), loss modulus (black), and damping ratio (dark grey) of the UFA (
ρ
= 7.6 mg/cm
3
). (e) Absorption process of toluene (stained with Sudan Black B) on water by the UFA within 5 s. (
Source
: Reproduced with permission from (123)).
Chapter 3: DEVICES BASED ON GRAPHENE AND GRAPHANE
Figure 3.1 Two-dimensional graphene honeycomb lattice.
Figure 3.2 Published papers on graphene.
Figure 3.3 Structures of graphene and graphynes. (a) Graphene. (b) α-graphyne. (c) β-graphyne. (d) 6,6,12-graphyne. In all these cases, only one resonance structure, that is, one of several equivalent Lewis structures, is shown.
Figure 3.4 Graphene films. (a) Photograph of a relatively large multilayer graphene flake with thickness ∼3 nm on top of an oxidized Si wafer. (b) Atomic force microscope (AFM) image of 2 μm by 2 μm area of this flake near its edge. gray for graphene and dark gray for SiO
2
surface. (c) AFM image of single-layer graphene. For details of AFM imaging of single-layer graphene, please check the original Figure in color. (d) Scanning electron microscope image of one of our experimental devices prepared from FLG. (e) Schematic view of the device in (d).
Figure 3.5 (a) The energy, E, for the excitations in graphene as a function of the wave numbers,
k
x
and
k
y
, in the
x
- and
y
directions. The black line represents the Fermi energy for an undoped graphene crystal. Close to this Fermi level, the energy spectrum is characterized by six double cones where the dispersion relation (energy vs momentum,
ħk
) is linear. (b) The computed band structure and density of states of graphene using DFT.
Figure 3.6 SEM image of a graphene transistor.
Figure 3.7 (a) Schematic of a double-gated graphene FED used in the experiments. (b) Optical micrograph of several FEDs fabricated from one graphene flake.
Figure 3.8 Left: two-input (
A
and
B
) logic gate incorporating one monolayer graphene transistor.
R
is the output resistance of the graphene transistor, which depends on the gate voltage
V
G
. Right: Structure of the fabricated G-FET. (a) Optical micrograph showing single-layer graphene flakes. (b) Optical micrograph of the structure of the final device. The device is back gated through the p-type Si wafer. (c) Schematic of the vertical structure of the device.
Figure 3.9 (a) Sketch of the double-gate bilayer graphene TFET: the channel length is 40 nm, and n
+
and p
+
reservoirs are 40 nm long with molar fraction
f
. The device is embedded in 3 nm-thick SiO
2
dielectric.
V
top
and
V
bottom
are the voltages applied the top and bottom gate, respectively. Gate overlap has also been considered. Below, band edge profile of the device in the OFF state; (b) Transfer characteristics of the double-gate BG-TFET for different
V
diff
. f is equal to 2.5 × 10
−3
and VDS = 0.1 V.
Figure 3.10 (a) Image of devices fabricated on a 2-inch graphene wafer and schematic cross-sectional view of a top-gated graphene FET. (b) The drain current, ID, of a graphene FET (gate length LG = 240 nm) as a function of gate voltage at drain bias of 1 V with the source electrode grounded. The device transconductance, gm, is shown on the right axis. (c) The drain current as a function of VD of a graphene FET (LG = 240 nm) for various gate voltages. (d) Measured small-signal current gain |h21| as a function of frequency
f
for a 240-nm-gate (⋄) and a 550-nm-gate (▵) graphene FET at VD = 2.5 V. Cutoff frequencies, fT, were 53 and 100 GHz for the 550-nm and 240-nm devices, respectively.
Figure 3.11 Graphene barristor. (a) A schematic diagram to show the concept of a GB. (b) False-colored scanning electron microscopy image of the GB before the top-gate fabrication process. (c) Current versus bias voltage characteristic of a GB at a fixed gate voltage
V
gate
= 0 V, showing a Schottky diode characteristic. The inset shows a TEM image of graphene/silicon junction. No native oxide or defect is seen in the image. (d) A photograph of ∼2000 GB arrays implemented on a 6-inch wafer.
Figure 3.12 The self-aligned graphene transistor. (a) Photo image of large-scale self-aligned devices with transferred gate stacks on glass substrate. (B) Optical image of self-aligned graphene transistors on 300-nm SiO
2
/Si substrate. Scale bar, 100 µm. (c) SEM image of a graphene transistor with transferred gate stack. Scale bar, 2 µm. (d) Cross-sectional TEM image of the overall device layout. Scale bar, 30 nm.
Figure 3.13 Graphene-BN resonant tunneling transistor. (a) Schematic diagram of the devices. (b) Measured current–voltage characteristics of one of the devices (device A) at 6 K. (c) Theoretical simulation of device A obtained by using the Bardeen model and including the effect of doping in both graphene electrodes.
Figure 3.14 CMOS-compatible, 30 nm programmable graphene transistor.
Figure 3.15 (a) Optical image of the device layout with ground-signal accesses for the drain and the gate. (b) (False color) SEM image of the graphene channel and contacts. The inset shows the optical image of the as-deposited graphene flake (circled area) prior to the formation of electrodes. (c) Schematic cross-section of the graphene transistor. Note that the device consists of two parallel channels controlled by a single gate in order to increase the drive current and device transconductance.
Figure 3.16 Integrated complementary graphene inverter. (a) A schematic of the fabricated inverter. (b) Scanning electron microscopy image of the fabricated inverter. (c) The circuit layout (power supply
V
DD
= 3.3 V).
Figure 3.17 Sample morphology and layout. (a) AFM images of the sample: large flat terraces on the surface of the Si-face of a 4H-SiC(0001) substrate with graphene after high-temperature annealing in an argon atmosphere. (b) Graphene patterned in the nominally 2-mm-wide Hall bar configuration on top of the terraced substrate. (c) Layout of a 7 mm
2
wafer with 20 patterned devices. Encircled are two devices with dimensions L¼ 11.6 mm and W¼ 2 mm (wire bonded) and L¼ 160 mm and W¼ 35 mm. The contact configuration for the smaller device is shown in the enlarged image. To visualize the Hall bar this optical micrograph was taken after oxygen plasma treatment, which formed the graphene pattern, but before the removal of resist.
Figure 3.18 (a) Circuit diagram of a four-port graphene RF frequency mixer. The scope of the graphene IC is confined by the dashed box. The hexagonal shape represents a graphene FET. (b) Schematic exploded illustration of a graphene mixer circuit.
Figure 3.19 Modulation mechanism and device characteristics of flexible and transparent all-graphene transistors. (a) A constellation diagram depicting five different digital modulation techniques demonstrated in this work. The z-axis, representing the frequency, is included to show the frequency modulated signals. (b) A plot of the transmittance as a function of the wavelength and an illustration of the all-graphene transistor structure (inset). (c) a photograph of graphene circuit on a transparent and bendable plastic substrate, and a microscopic image of an all-graphene transistor (inset). The scale bar is 10 μm.
Figure 3.20 Integrated monolayer graphene ring oscillator (RO). (a) Circuit diagram of a three-stage RO. (b) Optical microscope image of a small RO. (c) Schematic of a complementary graphene inverter composed of two FETs.
Figure 3.21 Graphene transparent electrodes for dye-sensitized solar cells.
Figure 3.22 Graphene electrodes can now be flexible and transparent.
Figure 3.23 Electron microscope images show a new material for transparent electrodes that might find uses in solar cells, flexible displays for computers and consumer electronics, and future “optoelectronic” circuits for sensors and information processing. The electrodes are made of silver nanowires covered with a material called graphene. At bottom is a model depicting the “co-percolating” network of graphene and silver nanowires. (a,b) FESEM images and corresponding schematics (insets) of Hybrid 1 and Hybrid 2 films, within circular transfer length measurement structures; in each case, concentric metal rings and gap where hybrid film is exposed are visible. (c) HRTEM image of Hybrid 2 film, showing edge of Ag (beneath SLG) and nearby SLG region. The silver lattice planes can be clearly seen underneath the transparent SLG. (d) Magnified view of FESEM image for Hybrid 2 showing the wrapping of underlying AgNWs by SLG. (e) A resistor network model for graphene-AgNWs co-percolating system.
Figure 3.24 Graphene solar cell diagram.
Figure 3.25 Energy returned on energy invested.
Figure 3.26 Left: A transparent graphene film transferred on a 35-inch PET sheet. Right: A graphene-based touchscreen panel connected to a computer.
Figure 3.27 Structure of graphane in the chair conformation. The carbon atoms are shown in gray and the hydrogen atoms in white. The Figure shows the hexagonal network with carbon in the sp
3
hybridization.
Figure 3.28 Structural studies of graphane via TEM. (a) Changes in the electron diffraction after ∼4 h exposure of graphene membranes to atomic hydrogen. (c) Distribution of the lattice spacing d found in hydrogenated membranes. The green dashed line marks the average value, whereas the red solid line shows (d) always observed for graphene (both before hydrogenation and after annealing). (c and d) Schematic representation of the crystal structure of graphene and theoretically predicted graphane.
Figure 3.29 (a) Optical micrograph of e-beam patterned sample, which contains 1 L, 2 L, and thick sheets of graphene. The squares and rectangles are cross-linked HSQ etch masks. Non-cross-linked HSQ has been removed by the developer. The 1 L area in the dashed square is 15 × 15 µm
2
in size. (b) The D band intensity of Raman map for the dashed square in (a). (c) Raman spectra taken at the center of 1 L and 2 L graphene squares (area: 4 × 4 µm
2
) shown in panel (a) before (dotted) and after (solid, displaced for clarity) hydrogenation. Data in panels (b) and (c) were obtained in ambient conditions with λexc = 514.5 nm. The employed laser power was 3 mW and focused onto a spot of ∼1 µm in diameter. The integration time for each pixel was 20 s.
Figure 3.30 Schematic of synthetic routes toward hydrogenated graphene.
Figure 3.31 The growth of large-area graphane-like film by RF plasma beam deposition in high vacuum conditions. Reactive neutral beams of methyl radicals and atomic hydrogen effused from the discharged zone and impinged on the Cu/Ti-coated SiO
2
/Si samples placed remotely. A substrate heating temperature of 650 °C was applied.
Figure 3.32 Optical images and Raman measurements of the as-produced graphane-like film. (a) Optical microscope image of the film transferred to a SiO
2
/Si substrate. The inset shows ripping along crystallographic directions. (b) The evolution of Raman spectra (532 nm laser wavelength) with increasing annealing temperature for as-produced graphane sample. (c–e) Raman maps of the D(1300–1400), G+D' = (1550_1650), and 2D (2650–2750). Scale bar, 4 µm. (f) Optical contrast image shows homogeneous monolayer graphane film. Scale bar, 4 µm.
Figure 3.33 Schematic illustration for catalytic hydrogenation of graphene.
Figure 3.34 Left: Four isomeric single-sheet graphanes. Side views are at left, top views at right. Right: The relative energy (in eV per CH; relative to single-sheet graphane A, 0 K) of some CH structures.
Figure 3.35 (a) Schematic diagram of six possible configurations of hydrogenated graphene with equivalent hexagonal hydrocarbon rings. (b) Crystal structures (side and top views) of graphane with chair, stirrup, twist-boat, boat-1, boat-2, and tricycle configurations, respectively. In figures, the gray balls correspond to carbon atoms with up and down hydrogenation, respectively, and the white balls are hydrogen atoms.
Figure 3.36 (a) Representative snapshot of the early hydrogenation stages from ReaxFF molecular simulations at 500 K. Nonbonded atomic H atoms are indicated in white and C-bonded ones in green. (b) Zoomed region indicating H frustrated domains formed. The triangle path shows that a sequence of up and down H atoms is no longer possible. (c) Representative snapshot of the final hydrogenation states. Extensive hydrogenation and multiple formed H domains are clearly visible.
Figure 3.37 (a): Free energies (Δ
G
) per carbon for graphane-A (chair1 type) as a function of the at various temperature; (b): Free reaction energies (Δ
G
) per graphene for partially hydrogenated graphene configurations as a function of the at 300 K.
Figure 3.38 Left: Four isomeric graphane nanotube (10,0) structures. Right: Four isomeric graphane nanotube (10,10) structures. For each type GN, front views are at left, side views at right.
Figure 3.39 Bandgap of four stacking graphanes (3D) as a function of pressure.
Figure 3.40 Left: The relaxed structures (van der Waals corrected) of (a) CH, (b) LiCH, (c) LiCH+H
2
, (d) LiCH+2H
2
, (e) LiCH+3H
2
, and (f) LiCH+4H
2
; Right: (a) and (b) are the side and top view of the optimized structures of pure CH, respectively.
Figure 3.41 Schematic graphane quantum dots.
Figure 3.42 Sketch of the simulated device. The channel here shown is graphane, but the very same structure has been considered for graphone-based FET. In the inset, the device transversal cross-section is shown.
Figure 3.43 Graphane/graphene superlattices fabrication and imaging. (a) Schematic illustration of fabrication of the graphane/graphene superlattices and subsequent fluorescence quenching microscopy (FQM) imaging. (b–d) FQM imaging of the graphene with different graphane/graphene patterns. The scale bars in b–d are 200 µm.
Figure 3.44 (a) Total electron phonon coupling (EPC) in graphane and MgB
2
, CaC
6
, diamond, and graphene; (b) Tc from the modified McMillan formula.
Figure 3.45 Left: Silicene on Ag (110), (a) high resolution filled state STM image revealing honeycomb arrangement (few honeycombs are drawn on the image); (b) ball model of the corresponding calculated atomic structure (dark grey balls for Ag atoms in the first layer; small grey balls for the top most Si atoms); Right: silicene on Ag (111) (a) Filled-state atomically resolved STM image of the clean Ag(111) surface. (b) Filled-state atomically resolved STM image of the same sample (without any rotation) after deposition of one silicon monolayer. (c) Proposed ball model of silicene on Ag(111) derived from both STM images (a) and (b) and from the observed (2√3 × 2√3)R30° LEED pattern.
Figure 3.46 Synthesized germanane in experiment.
Chapter 4: LARGE-AREA GRAPHENE AND CARBON NANOSHEETS FOR ORGANIC ELECTRONICS: SYNTHESIS AND GROWTH MECHANISM
Figure 4.1 (a) Illustration of carbon segregation at metal surface. (b) Optical microscope images of graphene films transferred on 300 nm SiO
2
/Si substrates. Images of the graphene films grown on different thicknesses of Ni layers and growth time. The sample grown on 100 nm thick Ni for 30 s shows monolayer domains as large as 20 × 20 m
2
. Various spectroscopic analyses of the large-scale graphene films grown by CVD. (c) SEM images of as-grown graphene films on thin (300 nm) nickel layers and thick (1 mm) Ni foils (inset). (d) An optical microscope image of the graphene film transferred to a 300-nm-thick silicon dioxide layer. The inset AFM image shows typical rippled structures. (e) Raman spectra (532-nm laser wavelength) obtained from the corresponding colored spots in (d).
Figure 4.2 Schematic diagrams of graphene growth mechanism on Ni (111) (a) and polycrystalline Ni surface (d). (b) Optical image of a graphene/Ni (111) surface after the CVD process. The inset is a three-dimensional schematic diagram of a single graphene layer on a Ni (111) surface. (e) Optical image of a graphene/polycrystalline Ni surface after the CVD process. The inset is a three-dimensional schematic diagram of graphene layers on polycrystalline Ni surface. Multiple layers formed from the grain boundaries. (c) Maps of
I
G′
/
I
G
of 780 spectra collected on a 60 × 50 µm
2
area on the Ni (111) surface and (f) 750 spectra collected on a 60 × 50 µm
2
area on the polycrystalline Ni surface.
Figure 4.3 (a) SEM image of graphene on a copper foil with a growth time of 30 min. (b) High-resolution SEM image showing a Cu grain boundary and steps, two- and three-layer graphene flakes, and graphene wrinkles. Inset in (b) shows TEM images of folded graphene edges. 1L, one layer; 2L, two layers. (c) SEM image of graphene transferred on SiO
2
/Si (285-nm-thick oxide layer) showing wrinkles, as well as two- and three-layer regions. (d) Optical microscope image of the same regions as in (c). (e) Raman spectra from the marked spots with corresponding colored circles or arrows showing the presence of one, two, and three layers of graphene.
Figure 4.4 Schematic diagrams of the possible distribution of C isotopes in graphene films based on different growth mechanisms for sequential input of C isotopes. (a) Graphene with randomly mixed isotopes such as might occur from surface segregation and/or precipitation. (b) Graphene with separated isotopes such as might occur by surface adsorption.
Figure 4.5 Optical micrograph and distribution of C isotopes in a FLG film grown on Ni. (a) An optical micrograph of a FLG film transferred onto a SiO
2
/Si wafer. (b) The corresponding Raman map of location of the G ba and (c) a typical Raman spectrum from this film, showing the film consists of randomly mixed isotopes (with an overall composition of 45%
13
C and 55%. Scale bars are 5 µm. Micro-Raman characterization of the isotope-labeled graphene grown on Cu foil and transferred onto a SiO
2
/Si wafer. (d) An optical micrograph of the identical region analyzed with micro-Raman spectroscopy. Integrated intensity Raman maps of (e) G
13
(1500−1560 cm
−1
), (f) G
12
(1560−1620 cm
−1
) of the area shown in (d). Scale bars are 5 µm.
Figure 4.6 (a) Schematic of growth mechanism of the adlayer graphene. TOF-SIMS mapping (200 × 200 µm
2
) of isotopically labeled multilayer graphene on Cu foil. (b–f) The
12
C isotope distribution images of graphene by TOF-SIMS after 6 s (b), 12 s (c), 18 s (d), 24 s (e), and 30 s (f) 1 kV Cs
1+
ion beam sputter. (g) The overall sum image of 36 total images. (h, i) The cross-sectional views of
12
C graphene from the marked
x
(h) and
y
(i) lines in (g). The color scale represents secondary ion intensity.
Figure 4.7 SEM images of partially grown graphene under different growth conditions:
T
(°C)/
J
Md
(sccm)/
P
Me
(mTorr): (a) 985/35/460, (b) 1035/35/460, (c) 1035/7/460, (d) 1035/7/160. Scale bars are 10 µm.
Figure 4.8 The average size of graphene grains grown for 30 min at 1000 °C on Cu foil using 30 ppm methane in Ar mixture at 1 atm, as a function of partial pressure of hydrogen. The inserts illustrate SEM images of the typical shapes under these different conditions. Note that perfect hexagons are observed only at higher hydrogen pressures. Irregularly shaped grains grown at low hydrogen pressure have smaller size second layers (and even third layers on some) in the centers of grains. Scales bars are 10 µm (top two images) and 3 µm (bottom two images).
Figure 4.9 The growth of HGFs on flat liquid Cu surfaces on W substrates. (a) Scheme showing CVD process for the synthesis of HGFs on liquid Cu surface. (b) SEM image of HGFs showing a compact assembly of HGFs in which the dark and bright parts represent HGFs and the Cu surface, respectively. (c) SEM image of a near-perfect 2D lattice composed of similar-sized HGFs. (d) SEM image of the sample for 2 h growth showing the continuous graphene film with uniform contrast.
Figure 4.10 (a) Monolayer graphene is derived from solid PMMA films on Cu substrates by heating in an H
2
/Ar atmosphere at 800 °C or higher (up to 1000 °C). (b) Raman spectrum (514 nm excitation) of monolayer PMMA-derived graphene obtained at 1000 °C. See text for details. (c) Room temperature
I
DS
–
V
G
curve from a PMMA-derived graphene-based back-gated FET device. Top inset,
I
DS
–
V
DS
characteristics as a function of
V
G
;
V
G
changes from 0 V (bottom) to −40 V (top). Bottom inset, SEM (JEOL-6500 microscope) image of this device where the PMMA-derived graphene is perpendicular to the Pt leads.
I
DS
, drain–source current;
V
G
, gate voltage;
V
DS
, drain–source voltage. (d) SAED pattern of PMMA-derived graphene. (e–g) HRTEM images of PMMA-derived graphene films at increasing magnification. In (g), black arrows indicate Cu atoms.
Figure 4.11 TEM images of carbon materials obtained from iron catalyst films with thicknesses of (a) 2.5, (b) 50, (c) 100, (d) 200 nm, (e) thickness of multilayer graphene as a function of catalyst thickness.
Figure 4.12 Processes for transfer of graphene films (“Gr” = graphene). The top-right and bottom-left insets are the optical micrographs of graphene transferred on SiO
2
/Si wafers (285 nm thick SiO
2
layer) with “bad” and “good” transfer, respectively. The bottom-right is a photograph of a 4.5 × 4.5 cm
2
graphene on quartz substrate.
Figure 4.13 Electrochemical exfoliation of graphene from Cu foil. (a) Schematic diagram of electrochemical cell used for the electrochemical exfoliation. (b–c) Optical images showing the “whole film” peeling of PMMA-covered graphene from the copper foil. (d) Graphene film was transferred onto a 4 inch wafer by the wetting transfer process.
Figure 4.14 (a) Synthesis of patterned graphene films on thin nickel layers. Etching using FeCl
3
(or acids) and transfer of graphene films using a PDMS stamp. Etching using BOE or hydrogen fluoride (HF) solution and transfer of graphene films. RT, room temperature (25 °C). The dry transfer method based on a PDMS stamp is useful in transferring the patterned graphene films. After attaching the PDMS substrate to the graphene (b), the underlying nickel layer is etched and removed using FeCl
3
solution (c). (d) Graphene films on the PDMS substrates are transparent and flexible. The PDMS stamp makes conformal contact with a silicon dioxide substrate. Peeling back the stamp (e) leaves the film on a SiO
2
substrate (f).
Figure 4.15 (a) Schematic illustration for synthesis, etching, and transfer of large-area graphene films. Transferring and patterning of graphene films grown on a metal/SiO
2
/Si wafer. Graphene/metal layers supported by polymer films are mechanically separated from a SiO
2
/Si wafer. After fast etching of metal, the graphene films can be transferred to arbitrary substrates and then patterned using conventional lithography. (b) A image of as-grown graphene film on 3 inch 300 nm thick Ni on a SiO
2
/Si substrate. (c) A transferred wafer-scale graphene film on a PET substrate.
Figure 4.16 Schematic of the roll-based production of graphene films grown on a copper foil. (a) The process includes adhesion of polymer supports, copper etching (rinsing), and dry transfer printing on a target substrate. A wet-chemical doping can be carried out using a set-up similar to that used for etching. (b–d) Photographs of the roll-based production of graphene films. (b) Roll-to-roll transfer of graphene films from a thermal release tape to a PET film at 120 °C. (c) A transparent ultralarge-area graphene film transferred on a 35 inch PET sheet. (d) A graphene-based touchscreen panel connected to a computer with control software.
Figure 4.17 (a) Schematic illustration of graphene transfer by R2R and hot pressing; (b) photograph of a 6 × 6 cm
2
graphene film transferred onto a SiO
2
/Si wafer by hot pressing; and (c) photograph of an 18 inch graphene film transferred on a glass substrate by hot pressing.
Figure 4.18 (a) Schematic illustrations of the CLT processes of as-grown graphene on Cu foil onto a substrate. Large-area graphene films transferred onto (b) Photograph of electrostatic discharging on the substrate using an electrostatic generator. (c) A SiO
2
/Si wafer and (d) a flexible PET substrate using the CLT technique.
Figure 4.19 Fabrication of SLG device array. (a) Schematic representation of device fabrication procedure (see main text for details). (b) Brightfield optical image of a typical sample substrate after fabrication. (c) Close-up brightfield image of the same sample. Graphene connecting the copper pad is just visible (boxed). Inset: Image of the device channel (100×, NA = 0.9). (d) Differential interference contrast image of a longer device. Upper inset: Raman spectra across the length of the graphene strip are highly uniform. Lower inset: brightfield image of the sample. All brightfield images have been contrast enhanced.
Figure 4.20 (a) Schematic representation of the process. Step 1: a thin layer of copper is evaporated on the dielectric surface, Step 2: During the CVD, Step 3: the metal dewets and evaporates, Step 4: leaving the graphene layer on the substrate. (b) The schematic illustration of the growth. Step 1: The CH
4
precursors dissociate into carbon species and migrate on Cu surfaces, where some of the carbon species diffuse downward through Cu grain boundary (GB). Step 2: The graphene layer formed on the Cu surface; meanwhile, the carbon atoms continue to diffuse through Cu GB and segregate at the Cu–insulator interface. Step 3: The graphitization of carbon atoms underlying Cu film leads to the formation of bottom layer graphene. Step 4: The large-area and continues graphene layers can be obtained directly on substrate after removing the top layer graphene, followed by wet-etching of Cu thin film. (c) Photo of 2 inch insulating substrates: Cu on SiO
2
(300 nm)/Si. (d) Photos of the as-grown bottom layer graphene on the corresponding substrate shown in (c).
Figure 4.21 (a) Graphene growth process (b) Raman spectra after pyrolysis of PS polymer films with a 50 nm thick Ni capping layer at 1000 °C. (c) Raman spectra after pyrolysis of PMMA polymer films with a 50 nm thick Ni capping layer at 1000 °C.
Figure 4.22 (a) Schematic illustration for transfer-free growth of graphene on a substrate. Carbon SAM materials are squeezed between the top metal layer and the substrate, where the top-most metal layer is etched after pyrolysis. (b) AFM image of octyl-SAM on a SiO
2
/Si substrate. The tapping mode was used to measure the thickness of SAM. A step was formed by removing half of the SAM layer with UV/ozone cleaning. (c) Cross-sectional HRTEM image after pyrolysis of octyl-SAM, showing bilayer graphene. (d) AFM image of graphene originated by octyl-SAM on the substrate after metal etching.
Figure 4.23 (a) Schematic drawing of the DAS process for directly depositing graphene films on nonconducting substrates. The diagrams represent (from left to right) the elementary steps in the DAS process, including deposition (and annealing) of Ni thin films on desired substrates (SiO
2
/Si or PMMA, glass), preparation of diffusion couple of C–Ni/substrate, annealing in Ar or air (25–260 °C) to form C–Ni/graphene/substrate and formation of graphene on desired substrates by etching away C–Ni diffusion couple, respectively. Representative (b) optical microscopy (OM) image, (c) Raman spectra from red, blue, and green spots showing the presence of one, two, and three layers of graphene, respectively, (from bottom to top) and (d) Raman map image of the G/2D bands of graphene grown at temperature
T =
160 °C for 5 min on SiO
2
(300 nm)/Si substrate. Scale bars, 4 µm (b and d).
Figure 4.24 Photographs of the process used for etching and transferring of G–GC films onto plastic substrates. (a) As-synthesized G–GC films on Cu/PI substrates. The inset image displays a large array of patterned G–GC films formed on the PI substrates. (b) Wet-chemical etching of the underlying Cu layers by FeCl
3
solution. (c) Washing and cleaning with deionized water. The patterned films were not easily damaged or detached from the plastic substrates during the chemical etching and rinsing. (d) A transferred G–GC film on a PI substrate. The inset image shows that the transferred samples on the plastic substrates exhibit clear contrast between the G–GC and the substrates. (e) Raman spectrum of the G–GC films transferred to the SiO
2
/Si substrates.
Figure 4.25 (a–c) TEM images of graphene nanosheet growth beyond the h-BN substrate, (d) HRTEM image of the interface between a graphene domain and h-BN substrate, (e) HRTEM image of a folded edge graphene layer enlarged from (c), and (f and g) SAED patterns of graphene/h-BN taken from (b) and (c), respectively.
Figure 4.26 (a) Raman spectroscopy of graphene on sapphire indicates that structural quality improves as the growth temperature is increased from 1425 to 1575 °C. Additionally, the 2D/G ratio (b) remains equal to or greater than 1.5 with a significant fraction of the 2D Raman spectra being fit to one or four Lorentzian curves (c) suggesting the presence of monolayer and bilayer graphene. Finally, Raman mapping and subsequent peak fitting of the 2D peak for a film grown at 1525 °C indicates >90% monolayer coverage (d).
Figure 4.27 Time-dependent growths of graphene dots and films on α-Al2O3 substrates. (a–e) AFM images taken after the reactions for 30, 60, 90, 120, and 150 min, respectively. (f) Raman spectra measured from samples (a) through (e). All the spectra are normalized with G peak intensities. (g) Coverage, IG′/IG, and IG/ID as a function of reaction time.
Figure 4.28 Synthesis process and morphological changes of graphene on SiO
2
/Si substrates. (a) Schematic diagram of the oxygen-aided CVD growth of graphene on a SiO
2
/Si substrate. (b) Initial surface of the SiO
2
/Si substrate, characterized by a uniform flat surface. (c) AFM height image of graphene sheets with a thickness of 0.659 nm. (d) AFM phase image of graphene sheets. (e) AFM image of 2D interconnected graphene networks. (f) AFM image of continuous graphene films. (g) Photograph of a graphene film on SiO
2
/Si substrate. The edge was removed using adhesive tape. Scale bar = 1 µm.
Figure 4.29 Proposed mechanism for growth of carbon fiber derived from polyacrylonitrile precursor.
Figure 4.30 Schematic illustration of a catalyst-free process for graphene on a silicon wafer. (a) Polyacrylonitrile polymer solution is spin-coated on top of a silicon oxide substrate, forming the starting material. (b) The polymer film is stabilized under air atmosphere and then carbonized under a mixture of H
2
/Ar gases, resulting in graphene film. (c) The as-grown graphene is directly applied as an electrode for a thin film transistor. And the graphene can be transferred onto another substrate through etching of the silicon wafer. The insets show photographs of the sample at each step in the process.
Figure 4.31 Structural analysis of the graphene prepared using a 0.5 wt% PAN polymer. (a) HRTEM image of the graphene. The inset shows the selected area electron diffraction (SAED) pattern of the graphene. (b–d) STM topographical images, which were obtained at a tunneling current of 10 pA-2 nA and a tip-bias voltage of 0.1–100 mV, of the graphene transferred to a HOPG. (b) Well-ordered hexagonal pattern (2 × 2 nm
2
). (c) Dislocation and superlattice pattern induced by impurities (such as oxygen and nitrogen) and point defect, respectively (5 × 5 nm
2
). (d) Disordered area (2 × 2 nm
2
). e, XPS survey spectra (C1s and N1s) for the graphene.
Figure 4.32 (a) Raman spectrum, (b) deconvoluted Raman spectrum, and (c) deconvoluted XPS C1s spectrum of the CNS synthesized from the 6 wt% pitch solution. The inset is an enlarged XPS spectrum.
Figure 4.33 Representation of (a) the molecular structure of camphor (a botanical hydrocarbon), (b) pyrolysis of camphor in an argon atmosphere to form a graphene constructed carbon film, (c) a deposited film on the quartz substrate showing very good transparency.
Figure 4.34 (a) Molecular structure of 1, the hexadodecyl-substituted superphenalene C
96
–C
12
; (b) 30, 22, 12, and 4 nm-thick TGFs on quartz (2.5 × 2.5 cm
2
) with “M,” “P,” “I,” and “P” letters inside, erased from the film before heat treatment; (c) transmission spectrum of the TGFs with different thicknesses.
Figure 4.35 Fabrication scheme and microscopy images of supported and suspended carbon nanosheets. (a) A 1 nm thick SAM of biphenyl molecules is irradiated by electrons. This results in a mechanically stable cross-linked SAM (nanosheet) that can be removed from the substrate and transferred onto other solid surfaces. When transferred onto TEM grids, nanosheets suspend over holes. Upon fabrication scheme and microscopy images of supported and suspended carbon nanosheets. (b) Optical microscopy image of the section of a 5 cm
2
nanosheet that was transferred from a gold surface to an oxidized silicon wafer (300 nm SiO
2
). Some folds in the large sheet are visible, and originate from wrinkling during the transfer process. (c) Optical microscopy image of a line pattern of 10 mm stripes of nanosheet. The pattern was fabricated by e-beam lithography and then transferred onto oxidized silicon. Note that the small lines are almost without folds. (d) SEM of four 130 mm × 130 mm holes in a TEM grid after a nanosheet (cross-linked biphenyl SAM) has been transferred onto the grid. Two left holes are covered by an almost unfolded nanosheet. The upper right hole shows some folds, whereas in the lower right hole the sheet has ruptured. (e) TEM image of a nanosheet transferred onto a TEM grid with 11 mm holes after pyrolysis at 1100 K. The hole is uniformly covered with an intact nanosheet. Some folds within the sheet are visible. Heating to T > 1000 K in vacuum (pyrolysis), nanosheets transform into a graphitic phase.
Figure 4.36 (a) Suggested model for the transition from PPC to amorphous carbon (b) Suggested model for the transition from PPC to ultrathin amorphous CNSs.
Figure 4.37 Apparatus used for the deposition of CNS.
Figure 4.38 (a) Top view SEM image of CNSs deposited on a Si substrate using 80% C
2
H
2
in H2, at 600 °C substrate temperature, 35 mTorr total pressure, and 1000 W RF power for 10 min. Inset: Enlarged SEM image shows the edge thickness of 1–2 nm. (b) Side view SEM of the C
2
H
2
CNSs shown in (a). (c) Top view SEM of typical (40% CH
4
in H
2
, 700 °C, 100 mTorr, and 900 W) CH4 CNSs deposited on a Si substrate for 20 min. (d) Side view SEM of the CH
4
CNSs shown in (c).
Figure 4.39 A schematic explanation of CNS growth model.: direction of the electric field near a substrate surface; CH
x
: carbon-bearing growth species impinging from gas phase; C
g
: growth species diffuse along CNS surface; H: atomic hydrogen impinging from gas phase; CH
y
: defects removed from CNS by atomic hydrogen etching effects.
Figure 4.40 Current density–voltage (
J–V
) curves of ITO-free solar cells comprising different CNS anode films and the conventional ITO-based cell. The inset shows
R
s
and
R
sh
of various solar cells that varied only in their respective anodes.
Chapter 5: Functionalization of Silica Nanoparticles for Corrosion Prevention of Underlying Metal
Figure 5.1 Unscheduled server downtime for various hardware/operating system configurations. (
Source
: Figure adapted from data from Reference 1.)
Figure 5.2 ASHRAE Environmental Classes for Datacenters. (
Source
: Reproduced with permission from Reference 10.)
Figure Scheme 5.1 Corrosion reaction for silver and copper in the presence of H
2
S.
Figure 5.3 Representative sulfidation curve. (
Source
: Based on data from Reference 17.)
Figure 5.4 Diagram of standard thick film resistor construction.
Figure 5.5 Cross-sectional schematic of a corrode resistor from within a sulfur-rich environment.
Figure 5.6 Optical image of resistor after being exposed to a sulfur-rich environment.
Figure 5.7 Example of an interdigitated comb coupon for deliquescent relative humidity dust corrosiveness testing.
Figure 5.8 Common silicone conformal coatings contain silica fillers for rheology and various silicones and catalyst to allow cure of the conformal coating.
Figure Scheme 5.2 Example of silicone curing reaction commonly used in conformal coatings.
Figure Scheme 5.3 Reaction of a halide with oxygen to produce silica.
Figure 5.9 Flame oxidation process for the preparation of fumed silica.
Figure 5.10 SEM image of aggregated fumed silica.
Figure 5.11 Nucleation and growth of particles. (
Source
: Adapted from References 55 59, 60.)
Figure Schemes 5.4 Hydrolysis reaction of alkoxysilane.
Figure 5.5 Condensation reaction of silicic acid.
Figure Scheme 5.6 Stöber reaction using an alkoxysilane.
Figure 5.12 Example preparation of SiO
2
by a modified Stöber process. By changing the concentration of water, various particle sizes in the nanometer region can be produced.
Figure 5.13 SEM micrograph of nearly monodisperse silica nanoparticles generated by modified Stöber process.
Figure 5.14 Silica nanoparticles generated by a modified Stöber process using different concentrations of water in the reaction. Larger particles appear opaque (left) in solution while smaller particles appear translucent (right).
Figure Scheme 5.7 Natural gas amine-based scrubbing process (68, 69).
Figure Scheme 5.8 Claus process to produce elemental sulfur (70).
Figure 5.15 In this work, two approaches were investigated for surface modification, an approach without a catalyst (top reaction) and an acid-catalyzed approach (bottom reaction). The weight percent represents the amount of mass added to the silica particle.
Figure 5.16 Example of formulation prepared containing phosphine-modified silica fillers. In this example, the DPPAS-modified silica was added at a concentration of 17 wt% along with the various catalyst and resins.
Figure 5.17 (Right) Resistor arrays which were coated with anti-corrosion silicone RTV formulations. (Left) Once the resistor arrays were coated, the printed circuit board cards were placed into a desiccator containing elemental sulfur followed by the addition to an oven at 105 °C.
Figure 5.18 DPPAS-modified silica filler formulation coated on an aluminum test bar prior to exposure in the flowers of sulfur environment (left image) and after 96 h of flowers of sulfur exposure (right image). Phosphine-modified silica conformal coating before (left) and after (right).
Figure 5.19 FTIR spectrum with the area blown up in the area to demonstrate the addition of phosphine–sulfur bond formation at ∼610 cm
−1
.
Figure 5.20 Time to failures of 10 Ω resistors coated with various conformal coating formulations.
Chapter 6: NEW NANOSCALE MATERIAL: GRAPHENE QUANTUM DOTS
Figure 6.1 (a) Description of GQDS and (b) conceptual structural models for edge-functionalized GQDs. (
Source
: Reproduced from Reference (30), with permission).
Figure 6.2 Conceptual description of the top-down and bottom-up approaches for synthesizing GQDs. (
Source
: Reproduced from Reference (30), with permission).
Figure 6.3 (a) Structures of three colloidal GQDs. (b) Synthesis of GQDs through a wet chemistry process. (
Source
: Reproduced from Reference (42), with permission).
Figure 6.4 Schematic synthetic process for GQDs by using HBC (1) as a precursor. (
Source
: Reproduced from Reference (42), with permission).
Figure 6.5 (a) A diagram for the synthesis of GQDs and GO by pyrolyzing citric acid (
Source
: Reproduced from Reference (48), with permission) and (b) preparation of GQDs by pyrolyzing glucose via MAH method. (
Source
: Reproduced from Reference (49), with permission).
Figure 6.6 On-top_vac configuration of the C60 molecule. The single-sided arrow indicates the top-down point of view. (
Source
: Reproduced from Reference (50), with permission).
Figure 6.7 Comparison of the growth mechanism of graphene nanoislands and QDs using C
2
H
4
and C60. (a) Highly mobile carbon adatoms from the dehydrogenation of C
2
H
4
. (b) Nucleation of the C adatom at the step edges (at <1L dose of C
2
H
4
). Large-sized, irregular shaped graphene islands (at <1L∼<10L dose of C
2
H
4
). (c, d) Corresponding STM images for the growth of graphene islands from C
2
H
4
. (e) C60 molecules adsorb on the terrace and decompose to produce carbon clusters with restricted mobility. (f) Temperature-dependent growth of GQDs with different equilibrium shape from the aggregation of the surface-diffused carbon clusters. (g, h) Corresponding STM images for the well-dispersed triangular and hexagonal equilibrium-shaped GQDs produced from C60-derived carbon clusters. (
Source
: Reproduced from Reference (50), with permission).
Figure 6.8 Series of STM images monitoring the transformation of trapezium-shaped GQDs to triangular-shaped GQDs at 1000 K. (a–c) The numbers in the images indicate the time lapse in seconds. Tunneling parameters:
V
= 1.4 V,
I
= 0.3 nA; image size, 25 × 12 nm
2
. (
Source
: Reproduced from Reference (50), with permission).
Figure 6.9 Mechanism of the hydrothermal cutting of oxidized GSs into GQDs: a mixed epoxy chain consisting of epoxy and carbonyl pair groups (left) ruptured under the hydrothermal treatment and led to a complete cut (right). (
Source
: Reprinted from Reference (55), with permission).
Figure 6.10 TEM images of (a) blue-luminescent (dark spot), (b) green-luminescent (dark spot) GQDs produced by hydrothermally cutting graphene sheets, (c) green-luminescent (dark spot) GQDs obtained by one-step solvothermal method. (
Source
: Reproduced from References (40, 42, 58), with permission).
Figure 6.11 (a) Representation of GQDs containing an oligomeric PEG diamine surface-passivating agent. (b) TEM image of the GQDs. (
Source
: Reprinted from Reference (59), with permission).
Figure 6.12 (a) Representation of the GQDs and GQDs-PEG by one-pot hydrothermal reduction. (b, c) The images of the dry GQDs-PEG under sunlight (left) and 365 nm UV lamp (right). (d)TEM images of blue-luminescent (dark spot) GQDs-PEG obtained by one-pot hydrothermal reaction. (
Source
: Reprinted from Reference (59), with permission).
Figure 6.13 (a) A graphene-based single-electron transistor. A 30 nm GQD is connected to contact regions through narrow constrictions of 20 nm wide graphene (Reprinted from Reference (42), with permission). (b) A scanning force microscope image of an etched GQD device with source (S) and drain (D) leads and a plunger gate (PG) for electrostatic tenability (Reprinted from Reference (46), with permission). (c) A SEM image of the photo-etched sample structure consisting of the upper small Dot (GQD, 90 nm) and the bottom SET (Diameter = 180 nm). (
Source
: Reprinted from Reference (47), with permission).
Figure 6.14 (a) SEM images of the etched parallel-coupled graphene double dot sample structure. Seven in-plane plunger gates around the dot for fine-tuning. (b) Schematic picture of the device on N-type Si (Reprinted from Reference (66), with permission). (c) SEM image of the structure of the designed multiple-gated sample. (d) Schematic of a representative device. (
Source
: Reprinted from Reference (67), with permission).
Figure 6.15 (a and b) TEM images of as-prepared GQDs with different magnifications, (c) the size distribution of GQDs, (d) an AFM image of the GQDs on Si substrate, and (e) the height profile along the line in (d). (
Source
: Reprinted from Reference (71), with permission).
Figure 6.16 The typical high-resolution TEM images of N-GQDs and photoimages of electrochemically synthesized N-GQDs aqueous solution before (a) and after (b) one month standing. (
Source
: Reprinted from Reference (72), with permission).
Figure 6.17 A scheme of the stacking structure of graphene layer(s) in a filtration-formed graphene film (a) and electrochemically produced GQDs (b), and the surface SEM images of the original graphene film (c) and the one after CV scan for 2000 cycles (d). (
Source
: Reprinted from Reference (74), with permission).
Figure 6.18 TEM images of GQDs taken from the Reference (73) in 20 nm scale and 5 nm scale. (
Source
: Reprinted from Reference (73), with permission.)
Figure 6.19 High-resolution TEM images of GQD1 and GQD2. (
Source
: Reprinted from Reference (80), with permission).
Figure 6.20 Schematics diagram of the synthesis of GQDs by chemical oxidation and cutting of µm-sized pitch-based carbon fibers (CF). (
Source
