Photo-enhanced chemical etched GaN LED on silicon substrate

In this study, GaN LEDs grown with an intermediate DBR on a Si substrate were chemically etched by 3 M KOH solution under UV light illumination. After 60 min of KOH etching, the hexagonal etch pits and randomized embossments were clearly imaged by SEM and AFM. The etch pits were generated at the threading dislocations, which are common for lattice mismatched growth of GaN on Si. The photoluminescence intensity at 380 nm was enhanced by approximately 21% after PEC etching. The enhanced PL intensity indicated that the generated etch pits and embossments increased the surface area, and effectively increased light scattering effects by randomizing the light rays and increasing the number of scattering events.