Investigation into the temperature dependence of electron leakage in GaN-based blue laser diode structures by numerical simulation

摘要

The electron leakage characteristics of GaN-based high-power blue laser diodes (LDs) can be strongly influenced by temperature. To address this aspect, we investigated the temperature dependence of the electron leakage current in an AlGaN electron-blocking layer (EBL) of an InGaN/GaN blue LD structure using numerical simulations. For most cases of the Al compositions and doping concentrations of the AlGaN EBL considered in this study, the electron leakage current decreases significantly with increasing temperature despite the increase in the thermal energy of electrons with respect to the temperature. As a result, the operation current of InGaN blue LDs does not decrease by electron leakage current as the temperature increases, and the LD performance could be improved with increasing temperature in some cases owing to the reduced electron leakage. This counter-intuitive temperature dependence results from the increased potential barrier for electrons with increasing temperature owing to the increased Mg acceptor activation in the EBL with temperature. Furthermore, the obtained simulation results are analyzed using a thermionic emission model, which successfully explains the temperature dependence of the electron leakage characteristics of InGaN blue LDs.