SKM 2023 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 28: Focus Session: Breakthroughs in wide-bandgap semiconductor laser diodes II

HL 28.2: Invited Talk

Wednesday, March 29, 2023, 15:30–16:00, POT 251

Breakthrough technologies to realize room-temperature continuous-wave deep-ultraviolet laser diodes — •Maki Kushimoto — Nagoya University, Nagoya, Japan

AlGaN-based UVC laser diodes operating at wavelengths are expected to be a low-cost, environmentally friendly, and highly efficient laser light source for a variety of applications. Although the pulsed operation of AlGaN-based laser diodes at UV-C wavelengths has been confirmed in the previous studies, continuous wave lasing without cooling was difficult because of the high operating voltage. In this study, we further reduced the threshold gain by improving the optical confinement and improved the threshold current density while lowering drive voltage by modification of device designs. The new design improved the optical confinement factor to the quantum wells from 4% to 6% , which has led to a significant reduction in threshold current density. Furthermore, A reduction in threshold voltage was achieved by reducing the lateral distance between the n- and p-electrodes by tapering the sides of the LD mesa. In the conventional structure, the presence of process-induced crystal defects forced a distance between the n and p electrodes, which was a major factor in increasing the operating voltage. This tapered mesa performs the role of suppressing crystal defects by controlling shear stress of mesa edge. As a result, room temperature CW lasing at a wavelength of 274 nm with a threshold current density of 4.2 kA/cm² and a voltage of 8.7 V was successfully achieved.