CATHODOLUMINESCENCE OF ALN-GAN SHORT-PERIOD SUPERLATTICES

Cathodoluminescence of AlN-GaN short period superlattice films was mea sured al 6 K, 77 K, and room temperature. The superlattice films were deposited using a switched atomic layer metalorganic chemical vapor de position process onto a buffer layer of either AIN or GaN, which was d eposited on basal plane sapphire substrates. The individual AlN and Ga N layers of the superlattice films ranged in thickness from 2.6 to 20. 8 Angstrom. The cathodoluminescence of these samples was measured at s everal electron acceleration voltages to allow depth profiling of the samples. This allows the region of the sample (superlattice film, buff er layer, and substrate) from which the spectral features originate to be determined. A spectral peak in the ultraviolet region above the 3. 5 eV band gay of GaN has been observed in all the superlattice samples studied to date. Our results indicate that the location of this peak is determined by quantum confinement in the GaN layers. (C) 1996 Ameri can Institute of Physics.