Sanghyun Lee
Dr. Sanghyun Lee is an Assistant Professor at Indiana State University with the focus on NAND flash memory, ReRAM, Photodiode, and Photovoltaics.
Dr. Sanghyun Lee is an Assistant Professor at Indiana State University with the focus on NAND flash memory, ReRAM, Photodiode, and Photovoltaics.
Germanium is an elemental semiconductor, which played an important role in the birth of the semiconductor but soon was replaced with silicon. However, germanium is poised to make a remarkable comeback in the semiconductor industry. With this increasing attention, this book describes the fundamental aspects of germanium and its applications. The contributing authors are experts in their field with great in-depth knowledge. The authors strongly feel that this contribution might be of interest to readers and help to expand the scope of their knowledge.
Go to the bookThe spectral responses in quantum efficiency provide essential information about current generation, recombination, and diffusion mechanisms in a photodetector, photodiode, and photovoltaic devices as the quantum efficiency is a function of the voltage and light biases and the spectral content of the bias light and/or location of the devices. Recently, P-type Kesterite thin-film solar cells are emerging as they have a high absorption coefficient (>104 cm−1) and ideal direct bandgap (1.4–1.5 eV), which make them a perfect candidate for photovoltaic application. However, a champion device from Zincblende (CdTe) or Chalcopyrite (CIGS) solar cells shows ~21% efficiency (<21.5%, First Solar and <21.7%, ZSW, respectively) while Kesterite devices suffer from severe losses with <12.6% efficiency. Furthermore, the maximum theoretical efficiency based on Shockley-Queisser limit is about 32.2%, which indicates there is much room for the improvement. Consequently, the implication from the current situation highlights the need for a systematic analysis of the loss mechanism in Kesterite devices. In this work, we carried out a systematic study of the efficiency limiting factors based on quantum efficiency to model the quantum efficiency response of current CZTSSe thin-film solar cells. This will provide the guidance for proper interpretation of device behaviors when it is measured by quantum efficiency.
Part of the book: Optoelectronics
This chapter focuses on characterization, modeling, and simulation about the type-II superlattices photodetector application. Despite dramatic improvements in type-II superlattices in the past 15 years, challenges still exist in InAs/GaSb and InAs/GaInSb superlattices: The diffusion current, Shockley-Read-Hall (SRH) recombination current, tunneling current, and surface leakage current at elevated temperature. To establish a set of modeling and simulation input parameters, in-depth materials and device characterization at different conditions are carried out for initial materials and device models. Based on input parameters, we will describe the development of analytical and numerical models of InAs/GaSb and InAs/GaInSb type-II superlattice-structured materials and device systems. At the end of this chapter, the fitting of modeled and simulated data will be performed to compare empirical data and modeling results at a set of temperature, which will provide guidance to achieve the higher performance.
Part of the book: Two-dimensional Materials for Photodetector