Semipolar InGaN blue laser diodes with a low optical loss and a high material gain obtained by suppression of carrier accumulation in the p-waveguide region

We obtained InGaN laser diodes (LDs) with a low optical loss (1.9 ± 0.6 cm−1) by utilizing an undoped In0.07Ga0.93N p-waveguide (p-WG) and a remote p-AlGaN electron blocking layer. This improvement, however, was accompanied by a low injection efficiency (37%) and a poor material gain. Electroluminescence measurements and energy band diagram simulations revealed excessive carrier accumulation in the p-WG region, which was suppressed by introducing an undoped indium-free GaN p-WG. This enabled LDs with a high material gain, a low optical loss (4.6 ± 0.7 cm−1), an improved injection efficiency (60%), and a peak light output power of 1.6 W at 1.5 A.