Correlation of Defects and Lasing Threshold for AlGaN Deep Ultraviolet Lasers Grown by Molecular Beam Epitaxy

Abstract

Herein, aluminum gallium nitride (AlGaN)/AlN double‐heterostructure (DH) laser at 287 nm with a lasing threshold of 530 kW cm−2 is shown. The laser structure is grown on the AlN‐on‐sapphire template by molecular beam epitaxy. This lasing threshold is drastically reduced compared with the previously reported AlGaN DH lasers at 297 nm with a threshold of around 1 MW cm−2. The detailed studies indicate that this improvement is mainly attributed to the control of defect formation largely due to the increased growth temperature of the AlGaN active layer. This is consistent with the improved internal quantum efficiency at low excitations. Moreover, the control of Al vacancy related point defects is clearly demonstrated by the absence of defect emission in the visible band.