Dry plasma technology for in-situ vacuum processing of HgCdTe infrared photodetectors

A fabrication procedure using dry plasma process technology has been developed for HgCdTe photoconductive detectors. Reactive ion etching (RIE) was used after the mesa delineation of detector elements to open contact areas in the passivation layer for metal deposition, and to take advantage of the increase in effective doping in HgCdTe material when it is exposed to RIE. The increase in the n-type doping in the contact areas provides a potential barrier to reduce carrier recombination at the semiconductor/metal interface, thereby improving detector responsivity, and removing one masking step from the fabrication process. Mid-wavelength infrared HgCdTe photoconductors fabricated using this procedure give a background limited D_λ ^* of 2.0×10¹¹ cmHz^1/2W^-1 at an operating temperature of 80 K