Current transport mechanism of Au∕Ni∕GaN Schottky diodes at high temperatures

Abstract

Current transport mechanism in Au∕Ni∕GaN Schottky diodes has been investigated using current-voltage characterization technique between 27 and 350°C. It is found that the ideality factor n of the diode decreases with increasing temperature when the temperature is lower than 230°C, and then increases with increasing temperature when the temperature is higher than 230°C. The corresponding Schottky barrier height (SBH) increases all through the temperature range. Thermionic-emission model with a Gaussian distribution of SBHs is thought to be responsible for the electrical behavior at temperatures lower than 230°C, while the generation-recombination (GR) process takes place in at temperatures above 230°C. The effective Richardson constant is determined to be 24.08Acm−2K−2, in excellent agreement with the theoretical value. The extrapolated activation energy of the GR process is determined to be 1.157eV. Based on the cathodoluminescence measurements, it is suggested that the deep level defects inducing yellow luminescence facilitate the GR process of the current transport in the diodes.