Arsenic Diffusion Study in HgCdTe for Low p-Type Doping in Auger-Suppressed Photodiodes

Controllable p-type doping at low concentrations is desired for multilayer HgCdTe samples in a P +/π/N + structure due to the promise of suppressing Auger processes, and ultimately reduced dark current for infrared detectors operating at a given temperature. In this study, a series of arsenic implantation and annealing experiments have been conducted to study diffusion at low Hg partial pressure with the goal of achieving effective control over dopant profiles at low concentration. Arsenic dopant profiles were measured by secondary ion mass spectroscopy (SIMS), where diffusion coefficients were extracted with values ranging between 3.35 × 10−16 cm2 s−1 and 6 × 10−14 cm2 s−1. Arsenic diffusion coefficients were found to vary strongly with Hg partial pressure and HgCdTe alloy composition, corresponding to variations in Hg vacancy concentration.