Effect of Native Defects on Optical Properties of InxGa1-xN Alloys

Effect of Native Defects on Optical Properties of In x Ga 1-x N Alloys S. X. Li and E.E. Haller, Materials Sciences Division, Lawrence Berkeley National Laboratory, and Department of Materials Science and Engineering, University of California, Berkeley, California 94720 K. M. Yu, W. Walukiewicz, J. W. Ager III, J. Wu, and W. Shan, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 Hai Lu and William J. Schaff Department of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853 Abstract: The energy position of the optical absorption edge and the free carrier populations in In x Ga 1-x N ternary alloys can be controlled using high energy 4 He + irradiation. The blue shift of the absorption edge after irradiation in In-rich material (x > 0.34) is attributed to the band-filling effect (Burstein-Moss shift) due to the native donors introduced by the irradiation. In Ga-rich material, optical absorption measurements show that the irradiation-introduced native defects are inside the bandgap, where they are incorporated as acceptors. The observed irradiation-produced changes in the optical absorption edge and the carrier populations in In x Ga 1-x N are in excellent agreement with the predictions of the amphoteric defect model. PACS numbers: 78.66.Fd, 78.40.Fy Electronic Mail: w_walukiewicz@lbl.gov