Optical studies of degradation of AlGaN quantum well based deep ultraviolet light emitting diodes

Aging under high current stress of AlGaN quantum well based light emitting diodes with high and low Al content in the wells emitting at 270 nm and 335 nm, respectively, has been studied by scanning near field optical spectroscopy and far field electroluminescence, photoluminescence and time-resolved photoluminescence. In the high Al content devices emission band related to optical transitions in the cladding involving nitrogen vacancies has been found. Evolution of this band during aging suggests that the role of N vacancies is crucial in the aging process by aiding defect generation and formation of high conductivity channels. (C) 2010 American Institute of Physics. [doi:10.1063/1.3506697]