Improvement of Electrical Properties of p-type GaN and Au Contact Interface

Abstract

In order to improve electrical conductivity of Mg-doped p-GaN, the enhancement of H release from Mg-doped p-GaN were attempted by applying current flow and electrical field through the p-GaN substrates during low temperature annealing. The microstructure and electrical properties after annealing were then investigated by transmission electron microscopy observation, direct current conduction test and Hall effect measurement. The results reveal that no reaction occurs between deposited Au film and GaN substrate during annealing at 573 K for 3600 s. The electrical conductivity does not show any improvement only by applying electrical field or by annealing at 573 K for 3600 s without current flow. It is likely due to the limited mobility of H within p-GaN. However, by applying current flow under the constant voltage of 30 V during annealing at 573 K for 3600 s, a significant improvement of the electrical conductivity has been observed. By applying electrical field and current flow during annealing at 573 K for 3600 s, the H release from p-GaN was enhanced and Mg was activated, resulting in increasing carrier concentration of acceptor and improving the electrical conductivity.