Electrical Characterization of Movpe-Grown p-Type GaN∶Mg Against Annealing Temperature

Abstract

Hall effect measurements have been applied for the electrical characterization of p-type Mg-doped GaN grown by metalorganic vapor-phase epitaxy on sapphire substrates in terms of annealing temperature for dehydrogenation (N₂ annealing) and hydrogenation (H₂ annealing) of the acceptors. With the N₂ annealing temperature from 600 to 900°C for dehydrogenation, both hole concentration and mobility increases, showing more activation of acceptors and less incorporation of unfavorable scattering centers probably originating from Mg-H bondings. The N₂ annealing at higher than the growth temperature results in reduced hole concentration, but the mobility gets higher. Some defects compensating acceptors may be induced at high temperature annealing, but they seem to be no scattering centers and be inactivated by successive hydrogenation and re-dehydrogenation at the optimum dehydrogenation temperature 900°C. The electrical degradation of GaN due to thermal damage is not very destructive and can be well recovered by annealing treatments.