Luminescence features of bulk crystals $\beta$-(Ga$_x$Al$_{1-x}$)$_2$O$_3$

This work is devoted to the study of the luminescence inhomogeneity nature of bulk (Ga$_x$Al$_{1-x}$)$_2$O$_3$ samples grown by the Czochralski method. In the study of sample cleavages by the local cathodoluminescence method, regions with different luminescence were observed. To determine the cathodoluminescence contrast nature, we studied the uniformity of the aluminum distribution, the surface topography, and compared the luminescence spectra and the kinetics of emission bands for different regions of the sample. Also, to determine the luminescence bands nature, the crystal was annealed in air at 1000$^\circ$C. This made it possible to observe the change in luminescence for the same region of the sample. Based on the studies performed, it was concluded that inhomogeneous luminescence is associated with the distribution of point defects. Upon annealing in air, the transformation of nonradiative recombination centers into luminescent centers was observed.