Ambient effects on Pb1-xSnxTe photodiodes

Summary form only given, as follows. In an effort to gain a better understanding of ambient effects on Lead-Tin Telluride photodiodes, we investigated the effects of various ambients on the electrical characteristics and the surface chemistry. Adsorption of oxygen on the surface of Pb
_l-x
Sn
_x
Te (where x = 0.20) was studied using Auger electron spectroscopy. Samples were heated by induction and exposed to dry, ultra-pure oxygen (99.9999%) in the temperature range of 100 - 500°C. Samples were also exposed to low pressure oxygen, water vapor, air and to vacuum annealing. All spectra showed selective chemical attack on the lead in the PbSnTe alloy. The low energy Auger peaks of lead are the result of different chemical states. Thus, the clean PbSnTe surface and the surfaces covered by chemisorbed oxygen could be associated with the occurrence of different lead Auger peak structures with little noticeable change in the tin and tellurium Auger peak structures. I-V characteristics of PbSnTe detectors were measured as a function of various treatments, including exposure to 0
₂
, N
₂
, H
₂
O (vapor) and vacuum bake-out. The results of these investigations are compared with the information obtained from the Auger spectroscopic analysis.