Effect of proton irradiation on the cathodoluminescence of gallium nitride films

Abstract

In this work, we studied the effect of 350 keV proton irradiation with two different fluences of 1013 cm−2 and 1015 cm−2 on the cathodoluminescence (CL) spectrum of GaN. Three lines were observed in the CL spectra of virgin and proton pre-irradiated samples - band edge line (3.4 eV), blue line (2.8 eV) and yellow line (2.15 eV). A strong decrease in the CL intensity for samples pre-irradiated by protons, especially at high proton fluence of 1015 cm−2, is shown. The evolution of the cathodoluminescence spectra during electron irradiation demonstrates a further decrease in all line intensities. It was shown that virgin and proton pre-irradiated GaN samples were not charged under electron irradiation. The cathodoluminescence signal drop can be caused by a decrease in the concentration of initial luminescence centers associated with intrinsic and impurity defects due to their transformation under proton bombardment and electron-stimulated diffusion implanted H+ ions.