Optical and microstructural properties of InGaN/GaN multiple quantum wells with embedded graphene coating

We investigate the effects of embedded graphene coating on the optical and microstructural properties of ultrathin InGaN/GaN multiple quantum wells (MQWs). The InGaN/GaN MQWs grown on graphene-buffered GaN templates displayed enhanced internal quantum efficiency compared to conventional ones and showed the internal electric field effect-free characteristic, desirable for general lighting applications. These phenomena were attributed to the enhancement of potential fluctuation with increased indium content and negligible piezoelectric polarization in ultrathin InGaN QWs, respectively. It was found that the atomically rough surface of GaN induced by embedded graphene coating efficiently relieved the biaxial compressive strain in the ultrathin InGaN/GaN QWs and enhanced the In incorporation efficiency during the InGaN growth, suggesting the potential use of atomic-thick carbon layer in niche optoelectronic applications. •InGaN/GaN multiple quantum wells (MQWs) were grown on a graphene-buffered GaN template.•The MQWs show improved optical properties compared to conventional ones.•The mechanism relies on the strain relaxation in InGaN QWs by graphene insertion.•The graphene coating layer can be used for the niche optoelectronic applications.