Probing The Indium Mole Fraction In An Ingan Epilayer By Depth Resolved Cathodoluminescence

Cathodoluminescence spectroscopy is used to depth profile the indium mole fraction of a 0.4 μm InGaN epilayer grown by metalorganic chemical vapour deposition, and to probe an underlying 1.0 μm GaN epilayer and the sapphire substrate beneath. Spectral information is obtained by using a variable energy electron beam as the excitation source. Calibration of beam penetration is achieved using Monte Carlo simulations of electron beam trajectories. The indium mole fraction is found to decrease from a mean value of 27% at the surface of the InGaN layer to ≈ 24% at its interface with the GaN layer.