Fermi Edge Singularity Observed in GaN/AlGaN Heterointerfaces

We observe sharp spectral lines, at energies which are higher than the bulk GaN band gap, in the photoluminescence and photoluminescence excitation spectra of GaN/AlGaN heterointerfaces grown by molecular beam epitaxy. The spectra and their temperature dependence are in accord with the Fermi edge singularity expected for two dimensional electron gas systems. The associated localized hole energy in the AlGaN interface side was extracted directly from the spectra.