Effects of Chip Size and Thermally Oxidized Al_xGa_2–xO₃ Sidewall on the Optoelectrical Characteristics of AlGaN-Based Deep Ultraviolet Micro-Light-Emitting Diodes

Abstract

The thermally oxidized Al x Ga 2−x O 3 sidewall was introduced to deep ultraviolet micro-light-emitting diodes (DUV μ-LEDs) to improve optoelectronic performance. Reducing the chip size of DUV μ-LEDs suppresses the current crowding effect and decreases the forward voltage (V f ) and dynamic resistance at a current density of 10 2 A/cm 2 . After the thermally oxidized Al x Ga 2−x O 3 sidewall was introduced, the V f and dynamic resistance in all DUV μ-LEDs with varying chip sizes increased. The V f and dynamic resistance are further increased by thickening of the thermally oxidized Al x Ga 2−x O 3 sidewall. The light output power densities of all DUV μ-LEDs with varying chip sizes were enhanced by introducing the thermally oxidized Al x Ga 2−x O 3 sidewall, and the light extraction efficiency could be improved. The light output power density was also enhanced by thickening the thermally oxidized Al x Ga 2−x O 3 sidewall. Although reducing the chip size of the DUV μ-LEDs increased the light extraction, the thermally oxidized Al x Ga 2−x O 3 sidewall further enhanced the light extraction of lateral light emission in the DUV μ-LEDs. In addition, the thermally oxidized Al x Ga 2−x O 3 sidewall enhanced the transverse magnetic polarized light emission in the DUV μ-LEDs, predominating the enhancement in the light output power density of DUV μ-LEDs.