Photoluminescence of Ga-face AlGaN/GaN single heterostructures

The radiative recombination in Ga-face Al0.30Ga0.70N/GaN single heterostructures (SHs) was studied by photoluminescence (PL) measurements. An energy shift of the excitonic transitions toward higher energies was observed, indicating the presence of residual compressive strain in the GaN layer. In addition to these exciton lines, a broad band energetically localized between the exciton lines and the LO-phonon replica was noticed in the undoped SH. From its energy position, excitation power dependence, as well as temperature behaviour, we have attributed this luminescence to the H-band (HB), which is representative of the two-dimensional electron gas (2DEG) recombination.