Emiliano R. Martins obtained his PhD in 2014 from the University of St. Andrews (UK) in the field of photonics, which deals with the interaction between light and matter in semiconductor devices. His research field involves solar cells and other optoelectronic devices and he has been teaching a course on semiconductor device physics since 2016 at the University of São Paulo in Brazil. He has written unpublished books for other undergraduate disciplines that he teaches, including signals and systems and digital signal processing.