| Summary: | 碩士 === 國立成功大學 === 微電子工程研究所碩博士班 === 96 === Devices with a vertical structure would allow a much large power handling capability due to the immune of current crowding effect. In this study, Vertical-conducting Metal-substrate GaN-based Light-Emitting Diodes (VM-LEDs) were fabricated by using of nickel electroplating substrate transformation in conjunction with laser lift-off (LLO) technique. To further improve light output power of VM-LEDs, a cost-effective and efficient surface roughening technology using polystyrene spheres (PSs) as an etching mask was proposed and demonstrated. Experimental results revealed that the proposed structure could effectively enhance extraction for VM-LEDs. As compare to VM-LEDs of the same size (1000×1000 µm2), electrical characteristics of the fabricated devices are similar, but with an enhancement in light output power by 36.82% at 350 mA.
To further improve light output power of LEDs, an IZO layer with a patterned surface was also formed atop the LEDs by using the proposed PSs nano-mask process. As compare to VM-LEDs with IZO TCL but without PS patterning, typical improvement in light output power under an injection current of 350 mA by about 19.4% has been obtained.
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