Transition from electron accumulation to depletion at InGaN surfaces

摘要

The composition dependence of the Fermi-level pinning at the oxidized (0001) surfaces of n-type In_xGa_(1-x)N films (0 ≤ x ≤ 1) is investigated using x-ray photoemission spectroscopy. The surface Fermi-level position varies from high above the conduction band minimum (CBM) at InN surfaces to significantly below the CBM at GaN surfaces, with the transition from electron accumulation to depletion occurring at approximately x=0.3. The results are consistent with the composition dependence of the band edges with respect to the charge neutrality level.