Hgcdte Lwir P-On-N Photodiodes Formed By Arsenic Diffusion From The Vapor Phase

We report current-voltage data for back-illuminated mesa photodiode test structures fabricated by arsenic-diffusion into n-type LPE HgCdTe films. Arsenic diffusion was carried out in a sealed quartz ampoule containing a source of both Hg and As. The arsenic-diffused p-on-n photodiodes were characterized at 70 K and 80 K. The cutoff wavelength was about 11 mu m at 80 K. The data for 400 mu m diameter photodiodes fabricated by the arsenic diffusion process are very similar to those from a conventional two-layer LPE P-on-n process for material with approximately the same cutoff wavelength. We outline process and doping level changes that should improve detector performance.