Room-temperature operation of AlGaN ultraviolet-B laser diode at 298 nm on lattice-relaxed Al 0.6 Ga 0.4 N/AlN/sapphire

An AlGaN ultraviolet-B laser diode at 298 nm was realized at room temperature using pulse operation. The laser diode has a lattice-relaxed Al0.6Ga0.4N layer from the underlying AlN/sapphire template and a composition-graded p-AlGaN cladding layer. The multimodal laser spectrum with proper polarization properties at 298 nm was obtained over the threshold current at 0.90 A corresponding to 67 kA cm–2. By broadening the width of the p-electrode to 11.5 μm, the threshold current density decreased to 41 kA cm–2.