Effect of Droop Phenomenon in InGaN/GaN Blue Laser Diodes on Threshold Current

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/cm^2 are similar, while LD with threshold current density of 4 kA/cm^2 exhibits a smaller auger-like recombination rate compared with the one of 6 kA/cm^2. 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.