Optically generated giant traps in high-purity GaN

Abstract

An unusual temperature dependence of the photoluminescence lifetime for the green luminescence (GL) band in GaN is explained. This GL is caused by an internal transition of electrons from an excited state to the ground state of the 0/+ transition level of the isolated ${\mathrm{C}}_{\mathrm{N}}$ defect. The excited state appears only after the ${\mathrm{C}}_{\mathrm{N}}$ defect captures two photogenerated holes. The electron capture by the excited state is nonradiative, yet the lifetime of such can be probed by the temperature variation of the GL lifetime, whose temperature dependence shows a classic case of electron capture by a giant trap.