Engineered ultraviolet InGaN/AlGaN multiple-quantum-well structures for maximizing cathodoluminescence efficiency

Abstract

We demonstrate a systematic way to understand and select the accelerating voltage for maximizing cathodoluminescence (CL) by correlating the carrier diffusion length with the efficiency of ultraviolet InGaN/GaN multiple quantum wells (MQWs). We showed that the MQWs absorption benefits from the absorbed energy within the diffusion length below the MQWs. With this understanding, we have achieved a good agreement on the dependence of acceleration voltage and QW number in InGaN/GaN MQW structures between the experimental data and the Monte-Carlo (CASINO) simulations. These findings indicate that CL-based UV generation from carefully engineered III-N MWQ structures with an appropriate number of QWs is highly promising. The understanding and application of this work can be extended to electron-beam pumped devices emitting in deep-UV (200-280 nm) wavelengths.