Carbon-nanotube-assisted nanoepitaxy of Si-doped GaN for improved performance of InGaN/GaN light-emitting diodes

Abstract

Using single-walled carbon nanotubes (SWCNTs) as nanomasks on an undoped GaN template, a significant biaxial stress relaxation was achieved in the subsequently-grown Si-doped n-GaN layer. Enhanced near band edge (NBE) emission intensity, similar free carrier concentrations, and the reduced peak width of the asymmetric (102) crystallographic plane all confirmed the suppression of threading dislocations due to the nanoepitaxial growth process. Temperature-dependent photoluminescence (PL) revealed improved internal quantum efficiency (IQE) of InGaN/GaN multi-quantum wells (MQWs) grown on this n-GaN layer. Furthermore, enhanced light output power and a remarkable reduction in efficiency droop were observed for the blue light-emitting diodes (LEDs), especially at higher injection currents. Our results emphasize the strong potential for SWCNTs as nanomasks in the heteroepitaxy of GaN-based devices without the exploitation of complicated lithography or etching processes.