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

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 degrees C-850 degrees 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 degrees 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.