Low resistance ohmic contact for p-type ZnTe using Au electrode

Abstract

We report low-resistive Au ohmic contact for a molecular beam epitaxy grown nitrogen doped p-type ZnTe (p-ZnTe:N) layer with high thermal stability, where the p-ZnTe surface is treated by oxygen plasma and HCl solution prior to Au film deposition. C contamination and native oxide layers of ZnTe are removed by oxygen plasma and HCl treatment, respectively, from the surface. As a result, a Te-rich layer is formed on the surface. The annealing temperature dependence of specific contact resistance is investigated. The specific contact resistance of Au ohmic contact for p-ZnTe:N with carrier concentration of 2×1018 cm−3 treated by oxygen plasma and HCl solution reaches as low as 5.8×10−6 Ω cm2 at an annealing temperature of 350 °C. This specific contact resistance value is the same as that of the reported Pd/(Pt)/Au contact for p-ZnTe:N with carrier concentration of 3×1019 cm−3, and clearly shows higher thermal stability.