Thermal Quenching of Photoluminescence from Er-Doped GaN Thin Films

摘要

The green (537 and 558 nm) and near infrared (1.54 micrometers) 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 integrated green Er(exp 3+) PL intensity (4S(sub 3/2)/2H(sub11/2)->4I(sub 15/2) remained nearly constant up to 150 K, but decreased at higher temperatures due to a less efficient Er(exp 3+) excitation. The integrated infrared Er(exp 3+) PL intensity (4I(sub 13/2)->4I(sub 15/2)) was found to be temperature- independent 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 simplified three-level model, the above-gap excitation cross-section was estimated to be approximately 10(exp -15) sq cm. This result indicates that Er(exp 3+) ions can be excited efficiently through carrier-mediated processes in a forward-biased GaN:Er light emitting device.