Ternary II-VI Alloys Promising for Application in Photodetectors

Abstract

In this chapter, an overview of II-VI semiconductors, especially some important ternary II-VI alloys, CdZnTe, CdHgTe, and HgZnTe, is given with more focusing on the applications in photodetectors. In this context, we investigate the solid-state physics of a photovoltaic device to provide a foundation to explain various considerations of manufacturing an II-VI-based photodetector and electronic properties that influence the photodetection efficiency of an II-VI alloy. Moreover, parameters which effect a photovoltaic device are discussed. The structural properties including crystal structures and their lattice parameters based on the composition of II-VI alloys as well as electronic and optical properties are introduced. A literature review related to the excellent properties of these alloys is presented to understand why they are chosen in detector technology. The dominant thermal diffusion current sources in II-Vis which are the Auger and Shockley-Read-Hall processes are discussed in detail. Then, in the following sections, we briefly focus on the applications of CdZnTe, HgCdTe, and HgZnTe ternary II-VI alloys as a photodetector. Herein, in addition to available detector performance of them, we give some important properties such as the wide bandgap, high crystalline perfection, and resistivity, which are required for improving the radiation detector performance. Some examples, most importantly, are given from the literature to understand how to accomplish these requirements and what are the obstacles to getting the detectors with desired properties. Finally, the effects of the size dimensionality on the performance of photodetectors are given.