Cathodoluminescence from an InGaN/GaN MQW grown on an epitaxially laterally overgrown GaN epilayer

In this paper we report room temperature CL studies of a 5 period InGaN (3 nm)/GaN (7 nm) multiple quantum well (MQW) with a nominal indium concentration of 15%, grown on and off a 4.8 μm epitaxially lateral overgrown GaN (ELOG) epilayer. The ELOG epilayer was overgrown through a SiO₂ striped mask with 3 μm window and SiO₂ stripe widths oriented in the GaN 〈11̄00〉 direction by metalorganic vapour phase epitaxy (MOVPE). We show that the luminescence efficiency of both the GaN and the MQW is improved for material lying above the stripes of the SiO₂ mask compared to that above the windows of the mask or unpatterned material. Monochromatic CL images were acquired from both the GaN and MQW layers with the emission from the MQW layer being much brighter than that from the GaN. Marked differences are observed between corresponding CL images acquired at different electron beam energies.