Enhanced performance of large-area vertical light-emitting diodes treated by laser irradiation

In this work, a comparative analysis of vertical light-emitting diodes (VLEDs) examining the device properties is performed with different surface treatment schemes. The VLEDs on graphite substrate are fabricated by the laser lift-off and the wafer bonding processes. The significance of KrF laser irradiation to form protrusions on the surfaces of undoped gallium nitride (u-GaN) and n-GaN is analysed in detail. The light output power of the fabricated VLEDs is significantly increased through the formation of micro-sized protrusions by the laser irradiation. For VLED irradiated with an energy density of 600 mJ/cm² on n-GaN surface with a thin u-GaN layer, the light output power is improved by 24.8% at 350 mA without degradation of electrical properties compared with that of the conventional VLED.