Structural Design of AlGaN Deep-Ultraviolet Laser at Wavelength 266.3 nm with Graded Electron Blocking Layer and Composite Quantum Wells/Barriers

Abstract

Deep-ultraviolet laser diodes (DUV LDs) are developing as vigorous light sources for sterilization, lithography, purification, and biochemical sensing. However, the development of high-performance deep-UV laser diodes is still limited by poor hole injection, which comes from the high activation energy of P-type dopants in wide-band gap AlGaN. This limitation reduces carrier transport efficiency and significantly restricts device performance. In this study, we focus on key performance parameters, including output power, injection efficiency, and the OCF (optical confinement factor), to address these challenges. Our design strategy involves minimizing the Al composition in the QWs (quantum wells) to improve carrier recombination while incorporating a graded AlGaN-based Mg-doped electron blocking layer to enhance hole injection and optical confinement within the active region. Results (simulation) confirm that the optimized device structure not only supports higher stimulated recombination rates but also strengthens the optical confinement. So, the proposed DUV LD achieves a 4.1% reduction in threshold voltage, a 27% decrease in threshold current (Ith), and a 7.5% increase in maximum output power at 100 mA input current, with the OCF reaching as high as 25%. These improvements clearly prove how careful material and structural engineering can overcome intrinsic limitations of AlGaN-based devices and lead to efficient and dependable deep-UV laser diode technology.