Room-temperature ultraviolet emission from GaN/AlN multiple-quantum-well heterostructures

We investigate the photoluminescence (PL) properties of GaN/AlN multiple-quantum-well structures grown by plasma-induced molecular-beam epitaxy by time-resolved PL spectroscopy. Despite the large strain induced by the lattice mismatch between GaN and AlN, the samples exhibit strong room-temperature UV emission characterized by a nonexponential decay that varies across the PL feature. The energy corresponding to the peak of the PL spectra varies as a function of the well width, in agreement with a calculation of the electron–hole (e1h1) transition energy that includes the large piezoelectric and spontaneous polarizations existing inside the wells. The thermal quenching activation energies of the emission intensity can be identified as the donor and acceptor binding energies.