Defects Responsible For Lifetime Degradation In Electron Irradiated N-Gan Grown By Hydride Vapor Phase Epitaxy

The effects of room temperature 6MeV electron irradiation on the donor concentration, deep trap spectra, and diffusion lengths of nonequilibrium charge carriers were studied for undoped n-GaN grown by hydride vapor phase epitaxy. Changes in these parameters begin at a threshold electron fluence of 5 x 10(15) cm(-2). The diffusion lengths after this fluence decrease by a factor of 3, accompanied by a drastic increase in the density of deep electron traps with the level near E-c-1 eV. There is a strong correlation between the changes in the density of these traps and the diffusion length of irradiated n-GaN, indicating that these centers control the lifetime in radiation damaged n-GaN. This is in sharp contrast to the starting material, where the lifetimes are controlled by other deep electron traps at E-c-0.56 eV. The concentration of the latter is not strongly affected by high energy electron irradiation. Published by AIP Publishing.