Suppression of unintentional carbon incorporation in AlGaN-based near-ultraviolet light-emitting diode grown on Si

Abstract

AlGaN-based near-ultraviolet light-emitting diodes (NUV-LEDs) emitting at 370 nm were grown on Si(111) substrates by metal-organic chemical vapor deposition. The effect of growth parameters of Si-doped n-type AlGaN thick layer on the material quality and optical performance was studied. Photoluminescence measurements showed that the near-band-edge emission of n-AlGaN was greatly increased and the yellow luminescence (YL) was substantially reduced, when the n-AlGaN layer was grown at a high temperature, a high chamber pressure, and a low growth rate. It was found that the reduced unintentional carbon incorporation in the n-AlGaN layer under those growth conditions was responsible for the improved optical property. The NUV-LED employing the optimized growth parameters of n-AlGaN showed an enhanced light output power and a suppressed YL emission, as well as a better color purity, as compared with the reference one. The results indicate that performance of NUV-LED can be significantly improved by suppressing unintentional carbon incorporation and the defects-related absorption/re-emission in the n-AlGaN.