Low resistance Ti/Al/Ni/Au Ohmic contact to (NH{sub}4){sub}2S{sub}x treated n-type GaN for high temperature applications

摘要

Low resistance Ti/Al/Ni/Au Ohmic contact to (NH{sub}4){sub}2S{sub}x treated n-type GaN has been studied in the temperature range from 25°C to 600°C. It is found that the specific contact resistivity ρ{sub}c of the sample treated with (NH{sub}4){sub}2S{sub}x solution for 5 min at 90°C decreases with increasing measuring temperature, while the ρ{sub}c of the sample treated with (NH{sub}4){sub}2S{sub}x solution for 25 min at 90°C increases with increasing measuring temperature. Excellent agreement with the "5 min-treated" sample can be obtained by the field emission model with an average Schottky barrier height (SBH) Φ{sub}B=1.05eV. Meanwhile, a field emission model with a temperature-dependent effective SBH is suggested to be responsible for the "25 min-treated" sample in which metal/semiconductor (MS) interface potential pinch-off may occur.