Photoluminescence due to inelastic scattering processes of excitons in a GaN thin film grown by metalorganic vapor phase epitaxy

We have investigated photoluminescence (PL) properties of a high quality GaN thin film grown by metalorganic vapor phase epitaxy under intense excitation conditions in a wide temperature range from 10 to 300 K. It is found that there are two types of PL band peculiar to intense excitation conditions. In a low temperature region below 80 K, the exciton-exciton scattering dominates the PL, the so-called P emission. On the other hand, in a high temperature region above ∼120 K, a PL band, which is different from the P emission, appears. The energy spacing between the new PL band and the fundamental A exciton linearly increases with an increase in temperature. In addition, the energy spacing is estimated to be zero at absolute zero temperature by extrapolation of the temperature dependence. These PL profiles indicate that the PL band observed in the high temperature regime originates from the exciton-electron scattering. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)