Enhancing Efficiency of AlGaN Ultraviolet-B Light-Emitting Diodes with Graded p-AlGaN Hole Injection Layer

Ultraviolet-B (UVB) AlGaN light-emitting diodes (LEDs) with a hybrid hole injection layer comprising a 5 nm thin p-Al_xGa_(1−x)N linearly graded layer (LGL), x from 0.65 to 0.50, and a 15 nm conventional p-AlGaN layer are proposed for ≈284 nm wavelength emission. The introduced p-Al_xGa_(1−x)N LGL effectively improves the confinement of the electrons in the active region by effectively increasing the conduction band barrier height. Moreover, it enhances the hole injection capability into the active region by energizing the holes that minimize the effective valence band barrier height. As a result, the proposed LED structure exhibits an incredibly reduced electron leakage, ten times lower than that of the conventional structure. Moreover, the output power and electroluminescence intensity of the proposed structure are enhanced by approximately twice at 60 mA current injection. Thus, the LGL LED structure can be a potential candidate for high-power UV light emitters.