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.

Direct Observation of Al Migration Enhancement by Changing the Al and N Source Relative Position in the Molecular Beam Epitaxy of AlGaN Nanowires

“…Moreover, considering the beam flux monitor (BFM) has different sensitivities for sources at different positions, the Al fluxes were calibrated carefully using both the N supply ,, and monitoring surface optical reflection signals without the presence of N on our previously developed smooth, droplet- and crack-free AlN-on-NW template, ,,, to ensure that both Al sources produce a similar amount of Al at the surface, despite the difference in flux reading. In our chamber configuration, both Al sources have a similar flux, with around 5% variation in the flux reading, when a similar amount of Al is produced at the surface.…”