Fabrication of vertical AlGaN-based ultraviolet-B laser diodes using a laser lift-off method

Vertical AlGaN-based UV-B laser diodes were fabricated by a laser lift-off method to exfoliate sapphire substrates. These devices were processed on 1 cm2 square wafers with a polycrystalline sintered AlN substrate as a structural support for the exfoliated device. Following electrode formation and other necessary processing steps, mirrors were formed through cleavage. Subsequently, the performance of the device was evaluated by injecting a pulsed current at room temperature. Results revealed distinct characteristics, including a sharp emission at 298.1 nm, a well-defined threshold current, strong transverse-electric polarization characteristic, and a laser-specific spot-like far-field pattern, confirming the oscillation of the vertical laser diode.