Reactive ion etching for mesa structuring in HgCdTe

Both wet chemical and dry plasma etching techniques have been investigated for mesa structuring in n- and p-type HgCdTe. Scanning electron microscopy (SEM) confirms the isotropic nature of a bromine-based wet chemical etching solution, and the anisotropic profile that results from reactive ion etching. Laser-beam-induced-current (LBIC) measurements reveal no significant modifications to the electrical properties for chemically etched HgCdTe material, but clearly demonstrate a p- to n-type conversion in p-type samples and n+ doping in n-type samples for reactive ion etching (RIE) (processing conditions: 400 mTorr, CH4/5H2, 0.4 W/cm2). LBIC measurements following low-temperature (200 °C) mercury annealing of RIE-processed samples indicate the full restoration of electrical properties to that of the initial as-grown wafers, thus preserving the beneficial aspects of RIE for anisotropic mesa structuring in HgCdTe.