Type conversion of p-(HgCd)Te using H-2/CH4 and Ar reactive ion etching

Hydrogen/methane gas mixtures and pure argon were used for reactive ion etching (RIE) of p-Hg1-xCdxTe (x approximate to 0.21 and 0.28). The effect of the H-2/CH4 ratio on the depth of the etched surface and the depth of the pn junction created under the etched surface were studied for the H-2/CH4 RIE process. It was found that the etch depth reaches a maximum at an H-2/CH4 ratio approximate to 0.8 and the depth of the pn junction decreases with increasing CH4 fraction in the mixture. The roughness of the etched surface is smallest using a gas mixture with a small amount of H-2 (20-30%). For the pure Ar RIE process the etch and pn junction depths were studied as functions of etch time, Ar pressure and rf power. Clear evidence for the creation of p-n junctions using various kinds of Ar RIE processes is found.