Growth of InGaN/GaN quantum wells with graded InGaN buffer for green-to-yellow light emitters

Abstract

We have studied the growth of high-indium-content InxGa1−xN/GaN double quantum wells (QWs) for yellow and green light emitters by plasma-assisted molecular beam epitaxy at a low substrate temperature (570 °C). By introducing a graded InyGa1−yN buffer layer, the PL intensity of QWs can be increased sixfold compared with that of the original structure. In addition, the indium content in InGaN QWs was increased owing the prolonged growth time of the graded InyGa1−yN buffer layer. After adjusting to optimal growth conditions, we achieved InxGa1−xN/GaN QWs with x = 0.32. Photoluminescence measurements showed that the emission wavelength from InxGa1−xN/GaN QWs was 560 nm (2.20 eV). The optimal condition for the gradient InyGa1−yN buffer layer was obtained for light emission from green to yellow.