A Plausible SAM IR APD with HgCdTe Heterojunctions
In this study, a plausible separate absorption and multiplication infrared avalanche photodiode (SAM IR APD) with HgCdTe heterojunctions was investigated, including a design method and a comparative study of multiplication layer (ML) designs. The selection of wavelength to be detected determines the energy bandgap of the absorption layer (AL). After this, there are two choices of the ML to make a SAM IR APD, one a larger bandgap material and the other smaller. In this study, electrostatic analysis, dark current modeling and simulation were performed on MWIR detecting HgCdTe APDs with three choices of the MLs. It is shown that the SAM IR APD with the larger band gap ML could provide great advantages in terms of extremely low dark current and high sensitivity. Hence, a SAM IR APD with larger bandgap ML can be used to realize high sensitivity and extremely low power IR APDs that are preferred for future applications.