Influence of Mg concentration in the AlGaN electron blocking layer on the temperature response of GaN-based near-UV laser diodes

Abstract

Temperature responses of the output characteristics of GaN-based near-UV laser diodes (LDs) with different Mg concentrations in the AlGaN electron blocking layer (EBL) were numerically investigated over the temperature range of 300–360 K under an ideal-interface assumption. The results show that increasing temperature raises the effective electron barrier and suppresses electron leakage, thereby improving the slope efficiency (SE). However, the magnitude of this improvement strongly depends on the Mg concentration in the EBL. At higher Mg concentrations, the additional improvement in SE becomes less pronounced at elevated temperatures, whereas the temperature-induced increase in threshold current (Ith) becomes more significant. Consequently, the output power continues to increase with temperature for LDs with low and moderate EBL Mg concentrations, whereas the LD with the highest Mg concentration exhibits performance degradation at elevated temperatures. These results indicate that the unfavorable temperature response provides an additional mechanism for the performance degradation associated with high EBL Mg concentrations, beyond the previously considered effects of optical absorption and Mg diffusion.