Yellow luminescence under spontaneous and stimulated emission conditions in GaN homostructures and heterostructures

In addition to the UV band-edge luminescence (3.4 eV), a yellow luminescence band (2.2 eV) has been found in GaN, which has been attributed to a deep level transition. The photoluminescence spectra of OMVPE grown epitaxial n-type GaN at different excitation intensities are reported. Photoreflectance measurements show that the UV luminescence peak at 3.4 eV is an intrinsic band-to-band transition. In addition, the luminescence from GaN and AlGaN/GaN heterostructures is studied in the stimulated emission regime.