Achievement of low p-type carrier concentration for MOCVD growth HgCdTe without an annealing process

Abstract

The electrical characteristics of as-grown epitaxial HgCdTe layers grown by metalorganic chemical vapor deposition were investigated. We propose a new cap layer in order to obtain as-grown HgCdTe layers with low p-type carrier concentration. The new cap layer called the “double-cap layer” consists of a graded Cd content Hg 1− x Cd x Te layer with x = 0.2–0.7 and a CdTe cap layer which was continuously grown at low temperature on the graded HgCdTe layer. The carrier concentration of HgCdTe layers with the new cap layer was about 3 × 10 16 cm −3. The p-type carrier concentration has been reduced further to 2 × 10 15 cm −3 (for x = 0.22) by lowering the growth temperature and increasing the partial pressure of Hg. This carrier concentration is lower than the estimated Hg vacancy concentration from considerations of the thermal equilibrium conditions.