We report on a study of the effects of thermal annealing and electron beam irradiation on the optical properties of In0.14Ga0.86N films. An increase in luminescence intensity greater that 3-fold was observed after annealing at 800°C for 5 minutes. A similar luminescence intensity increase was obtained under electron beam irradiation. After subsequent anneal at 600°C for 1 hour, the improved cathodoluminescence (CL) intensity of the 800°C annealed sample was unchanged, but the CL intensity of e-beam exposed sample reversed back to as-grown level. The improvement in luminescence intensity is attributed to breaking the N-H bond of un-reacted ammonia resulting from the low temperature MOCVD growth. It is suggested that un-reacted ammonia act as non-radiative recombination centers, which are dissociated and removed when annealed at a temperature greater than 800°C or locally dissociated by electrons during e-beam irradiation. This study shows approaches that can significantly improve the optical properties of InGaN, and can be potentially beneficial to InGaN-based optoelectronic devices.