Effect of Droop Phenomenon in InGaN/GaN Blue Laser Diodes on Threshold Current**Supported by the National Key Research and Development Program of China under Grant Nos 2016YFB0401803 and 2016YFB0402002, the National Natural Science Foundation of China under Grant Nos 61574160 and 61334005, the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No XDA09020401, and the Visiting Professorship

Abstract

Electroluminescence (EL) and temperature-dependent photoluminescence measurements are performed to study the internal quantum efficiency droop phenomenon of blue laser diodes (LDs) before lasing. Based on the ABC mode, the EL result demonstrates that non-radiative recombination rates of LDs with threshold current densities of 4 and 6 kA/cm2 are similar, while LD with threshold current density of 4 kA/cm2 exhibits a smaller auger-like recombination rate compared with the one of 6 kA/cm2. The internal quantum efficiency droop is more serious for LD with higher threshold current density. The internal quantum efficiency value estimated from temperature-dependent photoluminescence is consistent with EL measurements.