The abnormal aging phenomena in GaN-based near-ultraviolet laser diodes

An abnormal aging phenomenon is reported for GaN-based near-ultraviolet laser diodes (LDs). Under an electrical stress for several minutes, the threshold current of the LDs decreased, while the light output power and the operation voltage increased. The amplitude of the abnormal aging phenomena was found to be mainly related to the excess Mg concentration in the p-AlGaN electron blocking layer (EBL). It almost disappeared when the Mg concentration in the AlGaN EBL was reduced to 2 × 1019 cm−3. We propose that this phenomenon was related to the Mg–VN–H complex defects formed in highly doped AlGaN EBL ([Mg] > 3 × 1019 cm−3).