Mercury Cadmium Telluride E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Serie: Wiley Series in Materials for Electronic & Optoelectronic Applications
• Sprache: Englisch

Seitenzahl: 1104

Veröffentlichungsjahr: 2011

Beschreibung

Mercury cadmium telluride (MCT) is the third most well-regarded semiconductor after silicon and gallium arsenide and is the material of choice for use in infrared sensing and imaging. The reason for this is that MCT can be 'tuned' to the desired IR wavelength by varying the cadmium concentration. Mercury Cadmium Telluride: Growth, Properties and Applications provides both an introduction for newcomers, and a comprehensive review of this fascinating material. Part One discusses the history and current status of both bulk and epitaxial growth techniques, Part Two is concerned with the wide range of properties of MCT, and Part Three covers the various device types that have been developed using MCT. Each chapter opens with some historical background and theory before presenting current research. Coverage includes: * Bulk growth and properties of MCT and CdZnTe for MCT epitaxial growth * Liquid phase epitaxy (LPE) growth * Metal-organic vapour phase epitaxy (MOVPE) * Molecular beam epitaxy (MBE) * Alternative substrates * Mechanical, thermal and optical properties of MCT * Defects, diffusion, doping and annealing * Dry device processing * Photoconductive and photovoltaic detectors * Avalanche photodiode detectors * Room-temperature IR detectors

Leseprobe

Contents

Series Preface

Preface

Foreword

List of Contributors

Part One - Growth

Chapter 1: Bulk Growth of Mercury Cadmium Telluride (MCT)

1.1 INTRODUCTION

1.2 PHASE EQUILIBRIA

1.3 CRYSTAL GROWTH

1.4 CONCLUSIONS

REFERENCES

Chapter 2: Bulk Growth of CdZnTe/CdTe Crystals

2.1 INTRODUCTION

2.2 HIGH-PURITY Cd AND Te

2.3 CRYSTAL GROWTH

2.4 WAFER PROCESSING

2.5 SUMMARY

ACKNOWLEDGEMENTS

REFERENCES

Chapter 3: Properties of Cd(Zn)Te Relevant to Use as Substrates

3.1 INTRODUCTION

3.2 STRUCTURAL PROPERTIES

3.3 THERMAL PROPERTIES

3.4 MECHANICAL AND LATTICE VIBRONIC PROPERTIES

3.5 COLLECTIVE EFFECTS AND SOME RESPONSE CHARACTERISTICS

3.6 ELECTRONIC ENERGY-BAND STRUCTURE

3.7 OPTICAL PROPERTIES

3.8 CARRIER TRANSPORT PROPERTIES

REFERENCES

Chapter 4: Substrates for the Epitaxial Growth of MCT

4.1 INTRODUCTION

4.2 SUBSTRATE ORIENTATION

4.3 CZT SUBSTRATES

4.4 Si-BASED SUBSTRATES

4.5 OTHER SUBSTRATES

4.6 SUMMARY AND CONCLUSIONS

REFERENCES

Chapter 5: Liquid Phase Epitaxy of MCT

5.1 INTRODUCTION

5.2 GROWTH

5.3 MATERIAL CHARACTERISTICS

5.4 DEVICE STATUS

5.5 SUMMARY AND FUTURE DEVELOPMENTS

REFERENCES

Chapter 6: Metal-Organic Vapor Phase Epitaxy (MOVPE) Growth

6.1 REQUIREMENT FOR EPITAXY

6.2 HISTORY

6.3 SUBSTRATE CHOICES

6.4 REACTOR DESIGN

6.5 PROCESS PARAMETERS

6.6 METAL-ORGANIC SOURCES

6.7 UNIFORMITY

6.8 REPRODUCIBILITY

6.9 DOPING

6.10 DEFECTS

6.11 ANNEALING

6.12 IN SITU MONITORING

6.13 CONCLUSIONS

REFERENCES

Chapter 7: MBE Growth of Mercury Cadmium Telluride

7.1 INTRODUCTION

7.2 MBE GROWTH THEORY AND GROWTH MODES

7.3 SUBSTRATE MOUNTING

7.4 IN SITU CHARACTERIZATION TOOLS

7.5 MCT NUCLEATION AND GROWTH

7.6 DOPANTS AND DOPANT ACTIVATION

7.7 PROPERTIES OF MCT EPILAYERS GROWN BY MBE

7.8 CONCLUSIONS

REFERENCES

Part Two - Properties

Chapter 8: Mechanical and Thermal Properties

8.1 DENSITY OF MCT

8.2 LATTICE PARAMETER OF MCT

8.3 COEFFICIENT OF THERMAL EXPANSION OF MCT

8.4 ELASTIC PARAMETERS OF MCT

8.5 HARDNESS AND DEFORMATION CHARACTERISTICS OF MCT

8.6 PHASE DIAGRAMS OF MCT

8.7 VISCOSITY OF THE MCT MELT

8.8 THERMAL PROPERTIES OF MCT

REFERENCES

Chapter 9: Optical Properties of MCT

9.1 INTRODUCTION

9.2 OPTICAL CONSTANTS AND THE DIELECTRIC FUNCTION

9.3 THEORY OF BAND TO BAND OPTICAL TRANSITION

9.4 NEAR BAND GAP ABSORPTION

9.5 ANALYTIC EXPRESSIONS AND EMPIRICAL FORMULAS FOR INTRINSIC ABSORPTION AND URBACH TAIL

9.6 DISPERSION OF THE REFRACTIVE INDEX

9.7 OPTICAL CONSTANTS AND RELATED VAN HOVER SINGULARITIES ABOVE THE ENERGY GAP

9.8 REFLECTION SPECTRA AND DIELECTRIC FUNCTION

9.9 MULTIMODE MODEL OF LATTICE VIBRATION

9.10 PHONON ABSORPTION

9.11 RAMAN SCATTERING

9.12 PHOTOLUMINESCENCE SPECTROSCOPY

REFERENCES

Chapter 10: Diffusion in MCT

10.1 INTRODUCTION

10.2 SELF-DIFFUSION

10.3 CHEMICAL SELF-DIFFUSION

10.4 COMPOSITIONAL INTERDIFFUSION

10.5 IMPURITY DIFFUSION

REFERENCES

Chapter 11: Defects in HgCdTe – Fundamental

11.1 INTRODUCTION

11.2 NATIVE POINT DEFECTS IN ZINCBLENDE SEMICONDUCTOR

11.3 MEASUREMENT OF NATIVE DEFECT PROPERTIES AND DENSITY

11.4 AB INITIO CALCULATIONS

11.5 FUTURE CHALLENGES

REFERENCES

Chapter 12: Band Structure and Related Properties of HgCdTe

12.1 INTRODUCTION

12.2 PARAMETERS

12.3 ELECTRONIC BAND STRUCTURE

12.4 COMPARISON WITH EXPERIMENT

ACKNOWLEDGEMENTS

REFERENCES

Chapter 13: Conductivity Type Conversion

13.1 INTRODUCTION

13.2 NATIVE DEFECTS IN UNDOPED MCT

13.3 NATIVE DEFECTS IN DOPED MCT

13.4 DEFECT CONCENTRATIONS DURING COOL DOWN

13.5 CHANGE OF CONDUCTIVITY TYPE

13.6 DRY ETCHING BY IBM

13.7 PLASMA ETCHING

13.8 SUMMARY

REFERENCES

Chapter 14: Extrinsic Doping

14.1 INTRODUCTION

14.2 IMPURITY ACTIVITY

14.3 THERMAL IONIZATION ENERGIES OF IMPURITIES

14.4 SEGREGATION PROPERTIES OF IMPURITIES

14.5 TRAPS AND RECOMBINATION CENTERS

14.6 DONOR AND ACCEPTOR DOPING IN LWIR AND MWIR MCT

14.7 RESIDUAL DEFECTS

14.8 CONCLUSIONS

REFERENCES

Chapter 15: Structure and Electrical Characteristics of Metal/MCT Interfaces

15.1 INTRODUCTION

15.2 REACTIVE/INTERMEDIATELY REACTIVE/NONREACTIVE CATEGORIES

15.3 ULTRAREACTIVE/REACTIVE CATEGORIES

15.4 PASSIVATION OF MCT

15.5 CONTACTS TO MCT

15.6 SURFACE EFFECTS ON MCT

15.7 SURFACE STRUCTURE OF CdTe AND MCT

REFERENCES

Chapter 16: MCT Superlattices for VLWIR Detectors and Focal Plane Arrays

16.1 INTRODUCTION

16.2 WHY HgTe-BASED SUPERLATTICES

16.3 CALCULATED PROPERTIES

16.4 GROWTH

16.5 INTERDIFFUSION

16.6 CONCLUSIONS

ACKNOWLEDGEMENTS

REFERENCES

Chapter 17: Dry Plasma Processing of Mercury Cadmium Telluride and Related II–VIs

17.1 INTRODUCTION

17.2 EFFECTS OF PLASMA GASES ON MCT

17.3 PLASMA PARAMETERS

17.4 CHARACTERIZATION – SURFACES OF PLASMA-PROCESSED MCT

17.5 MANUFACTURING ISSUES AND SOLUTIONS

17.6 PLASMA PROCESSES IN THE PRODUCTION OF II–VI MATERIALS

17.7 CONCLUSIONS AND FUTURE EFFORTS

REFERENCES

Chapter 18: MCT Photoconductive Infrared Detectors

18.1 INTRODUCTION

18.2 APPLICATIONS AND SENSOR DESIGN

18.3 PHOTOCONDUCTIVE DETECTORS IN MCT AND RELATED ALLOYS

18.4 SPRITE DETECTORS

18.5 CONCLUSIONS ON PHOTOCONDUCTIVE MCT DETECTORS

ACKNOWLEDGEMENTS

REFERENCES

Part Three - Applications

Chapter 19: HgCdTe Photovoltaic Infrared Detectors

19.1 INTRODUCTION

19.2 ADVANTAGES OF THE PHOTOVOLTAIC DEVICE IN MCT

19.3 APPLICATIONS

19.4 FUNDAMENTALS OF MCT PHOTODIODES

19.5 THEORETICAL FOUNDATIONS FOR MCT ARRAY TECHNOLOGY

19.6 MANUFACTURING TECHNOLOGY FOR MCT ARRAYS

19.7 TOWARDS GEN III DETECTORS

19.8 CONCLUSIONS AND FUTURE TRENDS FOR PHOTOVOLTAIC MCT ARRAYS

REFERENCES

Chapter 20: Nonequilibrium, Dual-Band and Emission Devices

20.1 INTRODUCTION

20.2 NONEQUILIBRIUM DEVICES

20.3 DUAL-BAND DEVICES

20.4 EMISSION DEVICES

20.5 CONCLUSIONS

REFERENCES

Chapter 21: HgCdTe Electron Avalanche Photodiodes (EAPDs)

21.1 INTRODUCTION AND APPLICATIONS

21.2 THE AVALANCHE MULTIPLICATION EFFECT

21.3 PHYSICS OF MCT EAPDs

21.4 TECHNOLOGY OF MCT EAPDs

21.5 REPORTED PERFORMANCE OF ARRAYS OF MCT EAPDs

21.6 LGI AS A PRACTICAL EXAMPLE OF MCT EAPDs

21.7 CONCLUSIONS AND FUTURE DEVELOPMENTS

REFERENCES

Chapter 22: Room Temperature IR Photodetectors

22.1 INTRODUCTION

22.2 PERFORMANCE OF ROOM TEMPERATURE INFRARED PHOTODETECTORS

22.3 HgCdTe AS A MATERIAL FOR ROOM TEMPERATURE PHOTODETECTORS

22.4 PHOTOCONDUCTIVE DEVICES

22.5 PEM, MAGNETOCONCENTRATION, AND DEMBER IR DETECTORS

22.6 PHOTODIODES

22.7 CONCLUSIONS

REFERENCES

Index

Wiley Series in Materials for Electronic and Optoelectronic Applications

Series Editors

Dr. Peter Capper, SELEX Galileo Infrared Ltd, Southampton, UK

Professor Safa Kasap, University of Saskatchewan, Canada

Professor Arthur Willoughby, University of Southampton, Southampton, UK

Published Titles

Bulk Crystal Growth of Electronic, Optical and Optoelectronic Materials, Edited by P. Capper

Properties of Group-IV, III–V and II–VI Semiconductors, S. Adachi

Charge Transport in Disordered Solids with Applications in Electronics, Edited by S. Baranovski

Optical Properties of Condensed Matter and Applications, Edited by J. Singh

Thin Film Solar Cells: Fabrication, Characterization and Applications, Edited by J. Poortmans and V. Arkhipov

Dielectric Films for Advanced Microelectronics, Edited by M. R. Baklanov, M. Green and K. Maex

Liquid Phase Epitaxy of Electronic, Optical and Optoelectronic Materials, Edited by P. Capper and M. Mauk

Molecular Electronics: From Principles to Practice, M. Petty

Luminescent Materials and Applications, Edited by A. Kitai

CVD Diamond for Electronic Devices and Sensors, Edited by Ricardo S. Sussmann

Properties of Semiconductor Alloys: Group-IV, III–V and II–VI Semiconductors, S. Adachi

Forthcoming Titles

Silicon Photonics: Fundamentals and Devices, M. J. Deen and P. K. Basu

Photovoltaic Materials: From Crystalline Silicon to Third-Generation Approaches, Edited by G. J. Conibeer

Inorganic Glasses for Photonics: Fundamentals, Engineering and Applications, A. Jha, R. M. Almeida, M. Clara Goncalves and P. G. Kazansky

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Library of Congress Cataloging-in-Publication Data

Capper, Peter.Mercury cadmium telluride : growth, properties, and applications / Peter Capper and James Garland.p. cm.Includes bibliographical references and index.ISBN 978-0-470-69706-1 (cloth)1. Mercury cadmium tellurides. 2. Semiconductors – Doping. 3. Infrared detectors – Materials.I. Garland, James, 1933– II. Title.QC611.8.M38C37 2010661′.0726 – dc22

2010013107

P.C. – This book is dedicated to my wife Marian and our sons Samuel and Thomas for all their forbearance during the course of the book production.

J.W.G. – This book is dedicated to my wife Barbara for her love and encouragement.

Series Preface

WILEY SERIES IN MATERIALS FOR ELECTRONIC AND OPTOELECTRONIC APPLICATIONS

This book series is devoted to the rapidly developing class of materials used for electronic and optoelectronic applications. It is designed to provide much-needed information on the fundamental scientific principles of these materials, together with how these are employed in technological applications. The books are aimed at (postgraduate) students, researchers and technologists engaged in research, development and the study of materials in electronics and photonics, and industrial scientists developing new materials, devices and circuits for the electronic, optoelectronic and communications industries.

The development of new electronic and optoelectronic materials depends not only on materials engineering at a practical level, but also on a clear understanding of the properties of materials and the fundamental science behind these properties. It is the properties of a material that eventually determine its usefulness in an application. The series therefore also includes such titles as electrical conduction in solids, optical properties, thermal properties, and so on, all with applications and examples of materials in electronics and optoelectronics. The characterization of materials is also covered within the series in as much as it is impossible to develop new materials without the proper characterization of their structure and properties. Structure–property relationships have always been fundamentally and intrinsically important to materials science and engineering.

Materials science is well known for being one of the most interdisciplinary sciences. It is the interdisciplinary aspect of materials science that has led to many exciting discoveries, new materials and new applications. It is not unusual to find scientists with chemical engineering background working on materials projects with applications in electronics. In selecting titles for the series, we have tried to maintain the interdisciplinary aspect of the field, and hence its excitement to researchers in this field.

Peter CapperSafa KasapArthur Willoughby

Foreword

The first publication of the synthesis of the narrow-gap semiconductor alloy mercury cadmium telluride (MCT, HgCdTe or Hg1–xCdxTe) was a 1959 paper from the group at the Royal Radar Establishment in Malvern, England [1]. This seminal paper reported both photoconductive and photovoltaic response at wavelengths extending out to 12 μm and made the understated observation that this material showed promise for intrinsic infrared (IR) detectors.

Soon thereafter, working under a US Air Force contract [2] with the explicit objective of devising an 8–12 μm background-limited semiconductor IR detector that would operate at temperatures as high as 77 K, the group led by Dr Paul W. Kruse at the Honeywell Corporate Research Center in Hopkins, Minnesota devised a “modified” Bridgman crystal growth technique for HgCdTe. They soon reported in 1962 both photoconductive and photovoltaic detection in rudimentary HgCdTe devices [3].

The past 52 years have witnessed the evolution of HgCdTe into today’s pre-eminent and most widely applicable material for high-sensitivity IR detectors. Some of the fascinating early history of this half-century of research and development of HgCdTe was presented at a special symposium [4] celebrating the 50th anniversary of the first HgCdTe publication at a meeting of the Society of Photo-Optical Instrumentation Engineers (SPIE) held in Orlando, Florida on 13–17 April 2009.

The success of HgCdTe as today’s most broadly applicable high-performance IR detector material has come about because of the unique features of its energy band structure, together with a unique combination of technologically favourable material properties.

The HgCdTe energy band structure has three key features that make it the nearly ideal IR detector material: (i) tailorable energy band gap over the 1–30 μm range, (ii) large optical absorption coefficients that, together with long diffusion lengths, enable high quantum efficiencies (approaching 100% in most cases), and (iii) favorable inherent recombination mechanisms that lead to long carrier lifetimes, low thermal generation rates, high operating temperatures, and long diffusion lengths. An additional ideal feature of the HgCdTe band structure, only fully realized and exploited within the past 10 years, is that it truly enables ideal electron-initiated avalanche photodiodes, with single-carrier multiplication and no excess noise.

The favourable material properties of HgCdTe include: (i) the ability to grow bandgap-engineered films, with excellent lateral spatial uniformity and low EPD (<1 × 105 cm−2), by several epitaxial methods (LPE, MBE, MOVPE) onto IR-transparent lattice-matched CdZnTe substrates, (ii) the ability to grow films of useful quality by MBE and MOVPE on alternative substrates such as silicon, germanium and gallium arsenide, (iii) residual background carrier concentrations as low as 1 × 1014 cm−3, (iv) convenient n-type and p-type dopants, (v) versatile methods for forming mesa and planar homojunctions and heterojunctions, (vi) a low dielectric constant for low junction capacitance, (vii) a small change (0.3%) in lattice constant over the entire alloy range, and (viii) a native CdTe passivation that provides photodiodes with low 1/f noise and high radiation tolerance.

This combination of energy band structure and material properties has enabled a diverse family of high-performance quantum IR detectors, including photoconductors and both single-colour and two-colour photodiodes, which has led to large-format photovoltaic arrays that are the basis for a widely applicable hybrid focal plane array (FPA) technology.

Reviews and compendia of the basic material properties of this versatile variable band gap alloy have played a central role throughout the development of HgCdTe.

The first such compendium of HgCdTe basic material properties that I encountered after joining the Honeywell Radiation Center in Lexington, Massachusetts, in 1969 was an internal publication [5] by the research staff of the Honeywell Corporate Research Center in Hopkins, Minnesota, entitled “Basic Properties of Hg1–x Cdx Te.” The first edition was dated May 1970. The Preface began with these words:

“Hg1–xCdxTe is now established as the most important material for IR photon detectors. It is necessary therefore that we have the best possible understanding of those basic properties of this alloy system that are relevant to its use in IR detectors.”

   “This document is a sort of “handbook” of the basic physical properties of Hg1–xCdxTe; we will update it periodically as new and improved information becomes available. We can also use this document as a basis for planning experiments to improve our understanding of Hg1–xCdxTe, because those properties or parameters which are not yet well known and should therefore be studied further are clearly identified.”

This early Honeywell compendium came to be known as the “Gold Book” because of the colour of its front cover and was on the desk of all who worked on HgCdTe at Honeywell.

Since then, there have been a number of compendia and review volumes [6–21] of HgCdTe material and device properties, beginning with the review chapter by Don Long and Joe Schmit in Volume 5 of Semiconductors and Semimetals. These compendia and review volumes, many of which are multiply authored, have been central to the continual development and technological evolution of HgCdTe materials and devices.

Archival publications on the basic properties of HgCdTe materials and devices can also be found in the annual peer-refereed proceedings of the US Workshop on the Physics and Chemistry of HgCdTe and Related II–VI Materials. The 29th such workshop was held in New Orleans, Louisiana, in October 2010. The proceedings of the first 10 workshops were published as special issues of the Journal of Vacuum Science and Technology. The proceedings of subsequent workshops have been published as special issues of the Journal of Electronic Materials.

This newest review volume, edited by Peter Capper and James Garland, contains 22 chapters authored by internationally recognized experts in HgCdTe science and technology. The authors are from the USA, the UK, Japan, Belgium, Australia, China, and Poland.

This volume is divided into three parts: (i) Growth, (ii) Properties, and (iii) Applications. Part One, Growth, has 7 chapters covering bulk HgCdTe growth, growth and properties of CdZnTe substrates for HgCdTe epitaxy, alternative substrates (such as silicon, GaAs and InSb) for HgCdTe epitaxy, and epitaxial growth of HgCdTe by LPE, MOVPE and MBE. Part Two, Properties, has 10 chapters that cover mechanical, thermal, and optical properties, diffusion, native point defects, band structure, type conversion, surfaces and interfaces, superlattices, and dry processing. It is noteworthy that this is the first review chapter on dry processing of HgCdTe devices, a recognition of the increasing importance of dry etching in HgCdTe device formation. The five chapters in Part Three, Applications, cover photoconductors, photodiodes, non-equilibrium devices, dual-band photodiodes, emission devices, avalanche photodiodes, and room-temperature detectors. This is the first review chapter on HgCdTe avalanche photodiodes, a testimony of the importance of this newest type of HgCdTe device.

This volume is a welcome and worthy addition to the growing and critically necessary series of compendia on the fundamental properties of HgCdTe materials and devices.

Marion B. ReineBAE SystemsLexington, Massachusetts, USA

REFERENCES

[1] Lawson, W.D., Nielsen, S., Putley, E.H., and Young, Y.S. (1959) Preparation and properties of HgTe and mixed crystals of HgTe-CdTe. J. Phys. Chem. Solids, 9, 325.

[2] US Air Force Contract AF33(616)-7901, performed at Honeywell Research Center, Hopkins, Minnesota, P.W. Kruse, Principal Investigator; T.D. Pickenpaugh, Air Force Technical Monitor.

[3] Kruse, P.W., Blue, M.D., Garfunkel, J.H., and Saur, W.D. (1962) Long wavelength photoeffects in mercury selenide, mercury telluride and mercury telluride-cadmium telluride. Infrared Physics, 2, 53.

[4] HgCdTe: 50 year anniversary session. Infrared Technology and Applications XXXV, SPIE International Symposium on Defense, Security + Sensing, Orlando, Florida, April 13–17, 2009. Proceedings published in Proc. SPIE, 7298, 7298−2S (2009).

[5] Kruse, P.W., Long, D., Schmit, J.L., Scott, M.W., Speerschneider, C.J., and Stelzer, E.L. (1970) Basic Properties of Hg1−xCdxTe. Unpublished internal Honeywell document compiled by the research staff at the Honeywell Corporate Research Center, Hopkins, Minnesota, First Edition, May 1970.

[6] Long, D. and Schmit, J.L. (1970) Mercury-cadmium telluride and closely related alloys, in Infrared Detectors, Semiconductors and Semimetals, vol. 5, Chapter 5 (eds R.K. Willardson and A.C. Beer), Academic Press, New York.

[7] Weiler, M.H. (1981) Magnetooptical properties of Hg1–xCdxTe alloys, in Semiconductors and Semimetals, vol. 16, Chapter 3 (eds R.K. Willardson and A.C. Beer), Academic Press, New York.

[8] Kruse, P.W. and Ready, J.F. (1981) Nonlinear optical effects in Hg1–xCdxTe, in Semiconductors and Semimetals, vol. 16, Chapter 4 (eds R.K. Willardson and A.C. Beer), Academic Press, New York.

[9] Willardson, R.K. and Beer, A.C. (eds) (1981) Mercury Cadmium Telluride, Semiconductors and Semimetals, vol. 18, Academic Press, New York.

[10] Dornhaus, R. and Nimtz, G. (1983) The properties and applications of the Hg1–xCdxTe alloy system, in Narrow Gap Semiconductors, Springer Tracts in Modern Physics, vol. 98, Springer-Verlag, Berlin, pp. 119–300.

[11] Brice, J.C. and Capper, P. (eds) (1987) Properties of Mercury Cadmium Telluride, (EMIS Datareviews), INSPEC, Institution of Electrical Engineers, London.

[12] Capper, P. (ed.) (1994) Properties of Narrow Gap Cadmium-based Compounds, EMIS Datareviews Series, vol. 10, INSPEC, Institution of Electrical Engineers, London.

[13] Rogalski, A. (1995) Infrared Photon Detectors, SPIE Press.

[14] Capper, P. (ed.) (1997) Narrow-Gap II–VI Compounds for Optoelectronic and Electromagnetic Applications, Chapman & Hall, London.

[15] Rogalski, A., Adamiec, K., and Rutkowski, J. (2000) Narrow Gap Semiconductor Photodiodes, SPIE Press.

[16] Rogalski, A. (2000) Infrared Detectors, Gordon and Breach.

[17] Capper, P. and Elliott, C.T. (eds) (2001) Infrared Detectors and Emitters: Materials and Devices, Kluwer Academic Publishers, Boston.

[18] Henini, M. and Razeghi, M. (eds) (2002) Handbook of Infrared Detection Technologies, Elsevier. This book contains three review chapters on HgCdTe: MCT properties, growth methods and characterization, by R.E. Longshore, pp. 233–267; HgCdTe 2D arrays – technology and performance limits, by I.M. Baker, pp. 269–308; and Status of HgCdTe MBE technology, by T.J. de Lyon, R.D. Rajavel, J.A. Roth and J.E. Jensen, pp. 309–352.

[19] Piotrowski, J. and Rogalski, A. (2007) High-Operating-Temperature Infrared Photodetectors, SPIE Press.

[20] Kinch, M.A. (2007) Fundamentals of Infrared Detector Materials, SPIE Press.

[21] Chu, J. and Sher, A. (2008) Physics and Properties of Narrow Gap Semiconductors, Springer.

List of Contributors

Adachi, S.Graduate School of Engineering, Gunma University, Kiryu-shi, Gunma, Japan

Baker, I. M.SELEX Galileo Infrared Ltd, Southampton, UK

Becker, C. R.Physics Dept., Microphysics Laboratory, University of Illinois at Chicago, Chicago, Illinois, USA

Berding, M. A.SRI International, Menlo Park, California, USA

Capper, P.SELEX Galileo Infrared Ltd, Southampton, UK

Chang, Y.MicroPhysics Laboratory, Department of Physics, University of Illinois at Chicago, Chicago, Illinois, USA

Chu, J.Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, China

Dell, J. M.School of Electrical, Electronic and Computer Engineering, University of Western Australia, Australia

Faraone, L.School of Electrical, Electronic and Computer Engineering, University of Western Australia, Australia

Garland, J.EPIR Technologies Inc., Bolingbrook, Illinois, USA

Gordon, N.QinetiQ, Malvern, UK

Hirano, R.Compound Semiconductor Materials Production Dept, Nippon Mining & Metals Co., Ltd, Isohara Plant, Ibaraki, Japan

Jones, C.SELEX Galileo Infrared Ltd, Southampton, UK

Kinch, M.Infrared Technologies Division, DRS Technologies, USA

Krishnamurthy, S.SRI International, Menlo Park, California, USA

Kurita, H.Compound Semiconductor Materials Production Dept, Nippon Mining & Metals Co., Ltd, Isohara Plant, Ibaraki, Japan

Martyniuk, M.School of Electrical, Electronic and Computer Engineering, University of Western Australia, Australia

Maxey, C. D.SELEX Galileo Infrared Ltd, Southampton, UK

Musca, C. A.Centre for Electro-Optic Propagation and Sensing, University of Western Australia, Australia

Noda, A.Compound Semiconductor Materials Production Dept, Nippon Mining & Metals Co., Ltd, Isohara Plant, Ibaraki, Japan

Piotrowski, A.Vigo Systems S.A., 129/133 Poznanska St., 05-850 Ozarow Mazowiecki, Poland

Piotrowski, J.Vigo Systems S.A., 129/133 Poznanska St., 05-850 Ozarow Mazowiecki, Poland Technical University of Lodz, 116 Zeromskiego St., 90-924 Lodz, Poland

Sewell, R. H.School of Electrical, Electronic and Computer Engineering, University of Western Australia, Australia

Shaw, D.Department of Physics, University of Hull, Hull, UK

Sporken, R.University of Notre-Dame de la Paix, Namur, Belgium

Stoltz, A.US Army Night Vision and Electronic Sensors Directorate, Ft. Belvoir, Virginia, USA

Westerhout, R. J.School of Electrical, Electronic and Computer Engineering, University of Western Australia, Australia

Part One

Growth

1

Bulk Growth of Mercury Cadmium Telluride (MCT)

P. CAPPER

SELEX Galileo Infrared Ltd, Southampton, UK

1.1 Introduction

1.2 Phase equilibria

1.3 Crystal growth

1.3.1 Solid state recrystallization (SSR)

1.3.2 Traveling heater method (THM)

1.3.3 Bridgman

1.3.4 Accelerated crucible rotation technique (ACRT)

1.4 Conclusions

References

1.1 INTRODUCTION

In the early days of mercury cadmium telluride (MCT) production (1960s and 1970s) bulk growth techniques were the predominant ones. As time progressed into the 1980s and 1990s various epitaxial techniques, particularly liquid phase epitaxy (LPE), metal-organic vapor phase epitaxy (MOVPE), and molecular beam epitaxy (MBE) took over MCT production, particularly for photovoltaic devices, due to their greater flexibility. However, in some centers bulk-growth developments continued and material grown by bulk-growth techniques is still used for first-generation photoconductive IR detectors and for optical components in IR applications. Because of the sensitive nature of the R&D work associated with the material the history of MCT is characterized by most centers developing their own routes somewhat independently of their international counterparts.

There are two main types of bulk growth technique; from the liquid and from the vapor; however, most work on MCT is from the liquid phase and vapor-phase growth is not discussed in this chapter. Of the many bulk growth techniques applied to MCT three are seen to dominate. These are solid state recrystallization (SSR), the traveling heater method (THM), and Bridgman/accelerated crucible rotation technique (ACRT). This chapter covers the major developments in these three techniques, but first the key area of phase equilibria is discussed. These equilibria are critical to establish the understanding and limitations of all growth techniques.

Central to the successful use of these materials are the dual issues of elemental purity and cleanliness in all stages of preparation and handling, particularly prior to high-temperature heat treatments. A wide variety of assessment techniques have also been developed to characterize the compositional, electrical, and structural properties as well as chemical purity, but these are covered in a separate chapter in this book (Chapter 16).

1.2 PHASE EQUILIBRIA

Two types of equilibria are of interest. One is the solid compound in equilibrium with the gaseous phase (vapor growth) and the other is solid–liquid–gaseous equilibria (growth from liquid/melt). These phase equilibria also help in understanding post-growth heat treatments, either during cool-down or during annealing processes to adjust the stoichiometry, and hence electrical properties of compounds. Solid–liquid–gaseous equilibria are described by three variables: temperature (), pressure (), and composition (). It is, however, easier to understand the interrelations between these parameters by using two-dimensional projections such as – , – , and – plots.