Performance improvement of GaN-based laser diode by TMAH solution treatment on an m-plane-facet sidewall ridge structure

GaN-based laser diodes have been developed rapidly in recent years, but the hexagonal crystal system is not involved in the design of a ridge waveguide structure for an edge-emitting laser diode. In this study, m-plane was set to be the facet of the ridge sidewall of the GaN-based laser diode, which was etched by tetramethylammonium hydroxide (TMAH) solution to remove dry-etching damage and improve the device performance, with the threshold current decreasing from 194 mA to 183 mA, and the slope efficiency increasing from 0.49 W/A to 0.59 W/A. This work shows that the tilt and rough sidewall morphology after dry etching can be restructured by TMAH corrosion, accompanied by carrier injection efficiency improvement and internal loss reduction.