Electronic structure of oxygen deficient amorphous oxide semiconductor a‐InGaZnO4–x : Optical analyses and first‐principle calculations

摘要: Defect states in a representative amorphous oxide semiconductor, a-InGaZnO4, were studied by optical analyses and first-principle calculations. The suggested that the as-deposited a-IGZO film have weak subgap absorptions around 0.6 2 eV. Local density approximation calculations showed an oxygen defect works as electron trap well shallow donor depending on its local structure. It suggests large vacancy space remained deficient structure forms deep levels band gap traps electrons, while if such is annihilated e.g. growth process post thermal annealing, deficiency may form level. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)