Effect of Native Defects on Optical Properties of InxGa1-xN Alloys
  The energy position of the optical absorption edge and the free carrier populations in InxGa1-xN ternary alloys can be controlled using high energy 4He+ 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 InxGa1-xN are in excellent agreement with the predictions of the amphoteric defect model. 
S. X. Li, E.E. Haller, K. M. Yu, W. Walukiewicz, J. W. Ager III, J.   Wu, W. Shan, Hai Lu, and William J. Schaff