Temperature Dependence Of Internal Quantum Efficiency Of Radiation For The Near-Band-Edge Emission Of Gan Crystals Quantified By Omnidirectional Photoluminescence Spectroscopy

Internal quantum efficiency of radiation (IQE) for the near-band-edge (NBE) emission of freestanding-GaN crystals was observed by omnidirectional photoluminescence spectroscopy at various temperatures between 12 K and 300 K. A photoluminescence quenching ratio (R-q), defined by a spectrally integrated NBE emission obtained at 300 K to that obtained at 12 K, showed a lower value (2%) comparing with the IQE value (5.5%) for the GaN with the free electron concentration of 1 x 10(17) cm(-3)under cw photo-pumping density of 13 W cm(-2). This difference arises from the nonlinear relationship between IQE and the external quantum efficiency owing to the photon recycling effect.