Hydrogen passivation of deep levels in n–GaN

Abstract

Differential postgrowth hydrogen passivation of deep levels in n–GaN grown by metal-organic chemical vapor deposition has been directly observed by means of both deep level transient spectroscopy and deep level optical spectroscopy. Two deep levels found at Ec−Et=0.62 and 1.35 eV show strong H passivation effects, with their concentrations decreasing by a factor of ⩾30 and ∼14, respectively. The decrease in the 0.62 eV trap concentration together with its correlation with the presence of Mg in n–GaN is consistent with Mg–H complex formation. A band of closely spaced deep levels observed at Ec−Et=2.64–2.80 eV narrows to Ec−Et=2.74–2.80 eV after hydrogenation, consistent with hydrogen complexing with VGa3− defects as anticipated by earlier theoretical results. Finally, a deep level at Ec−Et=3.22 eV likely related to background acceptors remains unaffected by hydrogen.