N-type doping of InGaN by high energy particle irradiation

This article reviews our extensive studies of the effects of native defects introduced by high energy particles on the electrical and optical properties of InGaN alloys. We show that the electronic properties of irradiated InGaN can be well described by the amphoteric defect model. Because of the extremely low position of the conduction band edge of InN the formation energy of native donor defects is very low in Inrich InGaN alloys. High energy particle irradiation of InN and In-rich InGaN, will therefore produce donor defects and result in more n-type materials. As the irradiation dose increases, the electron concentration increases until the Fermi energy E _F approaches the Fermi stabilization energy E _FS. At this point both donor and acceptor-type defects are formed at similar rates, and compensate each other, leading to stabilization of E _F and a saturation of the electron concentration. Hence a large increase and then saturation in the Burstein-Moss shift of the optical absorption edge is also observed. Furthermore we also found that mobilities in the irradiated films can be well described by scattering from triply charged defects, providing strong evidence that native defects in InN are triple donors. The excellent agreement between the experimental results and predictions based on the ADM suggests that particle irradiation can be an effective and simple method to control the doping (electron concentration) in Inrich In _xGa _1-xN via native point defects. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.