Growth of (101¯1 ) semipolar GaN-based light-emitting diode structures on silicon-on-insulator

Abstract

The growth and characterization of (101¯1 ) semipolar GaN buffer, InGaN multiple quantum wells (MQWs), and light-emitting diode (LED) structure on patterned silicon-on-insulator (SOI) substrates, implementing the aspect ratio technique (ART), are reported. The early growth stages of GaN result in continuous and uniform stripes with small height variations that cause the formation of chevrons. Three coalescence strategies are tested to improve surface morphology and optical quality. Scanning electron microscopy identifies no crack formation but undulations of the surface. A roughness of ≈10 nm is measured by atomic force microscopy on large areas. The impact of MQW growth temperature shows similar surface morphology in terms of undulations and roughness. Room temperature photoluminescence spectra show wavelength emission redshifting when decreasing the MQW growth temperature. Room-temperature cathodoluminescence (CL) highlights first the presence of threading dislocations (TDs) in between the coalescence boundary despite the use of the ART technique. Second, CL shows a spatially homogeneous emission wavelength of around 485 nm only perturbed by lower-wavelength emission (455 nm) arising from the chevrons. Blue LED structures exhibit uniform emission wavelength at 450 nm, having a crack-free surface, and roughness of ≈5 nm. These results pave the way for the fabrication of semipolar micro-LEDs on SOI substrates.