AlGaN 1 AlN substrates 1 Aluminum gallium nitride 1 Aluminum nitride 1 Continuous wave lasing 1 Current injections 1 Diodes 1 Electric resistance 1 Electrode arrangement Epitaxial structure 1 III-V semiconductors 1 Peak wavelength 1 Semiconductor alloys 1 Semiconductor lasers 1 Series resistances 1 Single crystals 1 Threshold-current density 1 Ultraviolet 1 Ultraviolet laser diodes 1 Ultraviolet lasers 1 laser diode 1 ultraviolet 1