Effects of low energy e-beam irradiation on cathodoluminescence from GaN

We present cathodoluminescence (CL) studies on low energy e-beam irradiated (LEEBI) metal-organic vapor phase epitaxy (MOVPE) grown GaN films. High intensity LEEBI has been reported to reduce the band-edge photoluminescence intensity of MOVPE grown GaN films. Here we observe similar reduction of band-edge CL intensity with increasing LEEBI dose. The irradiation damage is found to be concentrated in the LEEBI energy dissipation depth by CL depth profiling. We have previously attributed the LEEBI induced reduction of band-edge intensity to the activation of in-grown Ga-vacancies. Here we observe no increase in the relative intensity of defect related yellow or blue CL emission peaks in the LEEBI treated samples. This indicates that blue or yellow emission in undoped GaN is not related to in-grown Ga-vacancies.