Reduction of the lasing threshold in optically pumped AlGaN/GaN lasers with two-step etched facets

Abstract

We report a two-step process to obtain smooth and vertical {10-10} m-plane facets in AlGaN/GaN separate confinement heterostructures designed to fabricate ultraviolet lasers emitting at 355 nm. The process combines inductively coupled plasma reactive ion etching with crystallographic-selective wet etching using a KOH-based solution. The anisotropy in the wet etching allows the fabrication of flat, parallel facets without degradation of the multilayer ensemble. The optical performance of the lasers is strongly improved (reduction of the lasing threshold by a factor of two) when using the two-step process for the definition of the cavity, in comparison to cavities fabricated by mechanical cleaving.

High-Aspect-Ratio GaN p–i–n Nanowires for Linear UV Photodetectors

“…Finally, wet etching in AZ400K (KOH containing developer) was used to smooth the NW sidewalls, removing the damaged material and exposing the m-{10−10} planes, 43 as illustrated in Figure 3e and shown in Figure 4d. Wet etching was performed at 65 °C for 6−8 h, depending on the desired NW diameter, resulting in an ∼60 nm/h etching rate of the NW sidewalls.…”

“…The fabrication process of top-down NWs is adopted from the two-step crystallographic-selective etching described in . Taking that information as a reference, we performed tests using both silica and polystyrene spheres, and we considered several diameters (details can be found in Supporting Information SI1).…”