Effect of Polarization‐Charge Modulation on the Carrier‐Injection Efficiency of AlGaN‐Based Ultraviolet‐B Laser Diodes Using Polarization Doping in the p‐Type AlGaN Cladding Layer

Abstract

In this study, the effect of polarization modulation on the carrier‐injection efficiency of AlGaN‐based ultraviolet‐B laser diodes (LDs) using polarization doping in the p‐type AlGaN cladding layer is discussed. The structure of an intentional Al‐content drop at the interface between the p‐type AlGaN electron‐blocking layer and the p‐type AlGaN cladding layer is investigated. First, the usefulness of this structure using a device simulator is confirmed. The optimized structure is also verified by fabricating devices. The fabricated devices are evaluated at room temperature and under pulsed operation. The carrier injection efficiency of the ultraviolet‐B LD is confirmed to exceed 10%. By utilizing a structure with Al‐content drops in the AlGaN, it is found that the peak optical output power is improved by a factor of 6.2 and the carrier‐injection efficiency by a factor of 3.3, compared to a case without this structure.