The effect of composite GaN/InGaN last barrier layer on electron leakage current and modal gain of InGaN‐based multiple quantum well laser diodes

Abstract

In order to enhance the optical confinement and to reduce the vertical electron leakage current of InGaN‐based multiple quantum well (MQW) laser diodes, a 2 nm GaN/5 nm In0.05Ga0.95N composite layer is designed as the last barrier layer between the MQW and AlGaN blocking layer in the p‐region. The device simulation shows that the laser diode then has a lower threshold current and a higher output light power under same injection current than the conventional laser diodes without such a composite barrier layer. It is found that the thickness of InGaN has little influence on the P–I characteristic, while the In composition significantly changes the threshold current and output light power properties of laser diodes, which is attributed to the enhanced optical confinement and reduced vertical electron leakage current escaping from active region to p‐doped region. The influences of the two parameters to modal gain are analyzed, too.