Cathodoluminescence study of InxGa1−xN quantum wells

We studied the cathodoluminescence spectra of ${\mathrm{In}}_x{\mathrm{Ga}}_{\text{1−x}}\mathrm{N},$ focusing on the spatial variation of the spectra. Strong inhomogeneity of cathodoluminescence spectra was observed on 22 nm thick ${\mathrm{In}}_x{\mathrm{Ga}}_{\text{1−x}}\mathrm{N}$ layers, where the peak energy varied up to 400 meV. In a double quantum well with a well width of 10 Å, the luminescence peak in a broad area spectrum was at 3.18 eV, but on some areas the peak was at 3.07 eV, the size of the area being about 1 μm. The variation of the cathodoluminescence spectra clearly indicates the presence of in-plane potential fluctuation in some ${\mathrm{In}}_x{\mathrm{Ga}}_{\text{1−x}}\mathrm{N}$ samples, although the cathodoluminescence spectra of most of our quantum wells optimized for devices were found to be uniform at least within the spatial resolution limit.