Effect of growth temperature of NH3-MBE grown GaN-on-Si layers on donor concentration and leakage currents

Abstract

The effect of growth temperature on the buffer leakage currents of GaN-on-Si layers grown by the NH3-MBE technique within the technologically acceptable temperature range (750 °C-850 °C) has been investigated. It is shown that the lowest leakage currents are exhibited by GaN layers grown at elevated growth temperature (growth temperature 825 °C, buffer leakage current 1 mA/mm at electric field strength 41 kV/cm). The photoluminescence technique was used to study the defects in GaN layers grown at different growth temperatures and to estimate the number of neutral donors in GaN-on-Si layers. A correlation between leakage currents, structural perfection and donor concentration in GaN-on-Si layers was established. It was found that the reduced growth temperature can lead to the formation of inversion domains in GaN-on-Si layers grown by the NH3-MBE technique.