Study of Defect Levels in the Band Gap for a Thick InGaN Film

Abstract

Deep-level transient spectroscopy, thermal admittance spectroscopy (TAS), and deep-level optical spectroscopy techniques have been used to investigate the defect levels in the band gap of a non-doped In0.09Ga0.91N film with a thickness of 300 nm. At temperatures ranging from 10 to 450 K, TAS analysis revealed defect levels at ∼7 meV under the conduction band (Ec) which were homogenously distributed in the InGaN film. The defect levels are considered to be attributed to the residual carrier density, probably originating from indium fluctuations and/or nitrogen vacancies (VN). Compared with the defect density of GaN, the defects of the InGaN film corresponding to the cation vacancies (VIII) and/or the VIII–O complex at 2.07 eV, and the shallow acceptor carbon (CN) defect at 3.05 eV, respectively, were remarkably enhanced. The possible increase of these defects is discussed in terms of VN and its complex with VIII that have been induced in the InGaN film.