Yellow and green bands in GaN by resolved spectral photoconductivity

Defect-related bands and their properties are widely investigated in gallium nitride, especially by luminescence techniques, which evidenced a broad yellow band, and seldom, a green band. We present here a study of the visible portion of the photoconductivity spectra obtained in samples of different thicknesses and doping. The superior resolution of photoconductivity with respect to luminescence techniques allows for clearly distinguishing green and yellow bands, both showing a double peak structure. Moreover, while the yellow band shape results were unchanged with sample properties, the green band is sensitive to the growth conditions. Hence some hypotheses about their microscopic origin can be proposed.