Theoretical and Experiment Study of Cathodoluminescence of GaN

Abstract

In this work, we report the theoretical and experimental results of cathodoluminescence (CL) from GaN layers with thickness (1-3) micron grown at 800°C by MOVPE on silicon substrate. The CL measurements were performed in a digital scanning electron microscope DSM 960 at room temperature. The CL spectra recorded at room temperature (RT) show the main UV peak at 3.42 eV of the fundamental transition and a broad yellow band at 2.2 eV attributed the intrinsic defects and extrinsic dopants and impurities. The simulation of the CL excitation and intensity is developed using consistent 2-D model based on the electron beam energy dissipation and taking into account the effects of carrier diffusion, internal absorption and the recombination processes in GaN. Then, we have investigated the evolution of the CL intensity from GaN as a function the electron beam energy in the range Eo= (5-20) keV. A comparative study between experimental and simulated CL spectra at room temperature is presented.