Hydrogen passivation of Zn acceptors in InGaAs during reactive ion etching

It is shown that the use of hydrogen-containing gases such as CHF3/H2, CHF3, CH4/H2, and CH4/He in reactive ion etching processes leads to a drastic reduction of the concentration of electrically active acceptors in a thin layer at the surface of highly Zn-doped InGaAs. This passivation effect leads to strongly nonlinear current/voltage characteristics of nonalloyed Ti/Pt/Au contacts when applied directly on as-treated p++-InGaAs layers. The observed deactivation of acceptors is inferred to be caused by hydrogen since no such effect was found with the use of hydrogen-free etching gases.