Damage-free substrate removal technique: wet undercut etching of semipolar 202¯1 laser structures by incorporation of un/relaxed sacrificial layer single quantum well

Abstract We applied a damage-free substrate removal technique using photoelectrochemical etching (PECE) by incorporating sacrificial layer In 0.12 Ga 0.88 N single quantum well (SL-SQW) types in semipolar ( 20 2 ¯ 1 ) flip-chip laser diode (FC-LD) structures. Although 40 nm type I promoted the development of high-quality green active region devices in terms of managing strain relaxation, processing was required under low-temperature KOH. However, 10 nm type II exhibited a smooth n-type GaN surface with room-temperature KOH, thereby promoting the applicability of the proposed technique for either a short light emitter or a combination with type I. The temperature-dependent PECE of SL-SQW types is important in realizing advanced FC-LDs.