hermal quenching of photoluminescence from Er-doped GaN thin films

The green (537 and 558 nm) and near infrared (1.54 mm) photoluminescence (PL) spectra of Er-doped GaN thin films have been investigated as a function of temperature, excitation wavelength, and pump intensity. Thermal quenching measurements showed that the 31 4 2 4 integrated green Er PL intensity ( S / H → I ) remained nearly constant up to 150 K, but decreased at higher temperatures 3 / 2 11 / 2 15 / 2 31 31 4 4 due to a less efficient Er excitation. The integrated infrared Er PL intensity ( I → I ) was found to be temperature-independent 13 / 2 15 / 2 up to 250 K, but decreased slightly at higher temperatures due to the onset of non-radiative decay. Pump intensity PL studies revealed that the above-gap excitation cross-section is more than two orders of magnitude greater than the below-gap excitation cross-section. Within a 216 2 31 simplified three-level model, the above-gap excitation cross-section was estimated to be |10 cm . This result indicates that Er ions can be excited efficiently through carrier-mediated processes in a forward-biased GaN:Er light emitting device.  2002 Elsevier Science B.V. All rights reserved.