| Summary: | 碩士 === 中原大學 === 機械工程研究所 === 100 === Roller imprinting technology was applied to fabricate nano scale structures of patterned sapphire substrate (PSS) to enhance the optical efficiency of light emitting diodes (LEDs).
In this study, a soft polymer such as polydimethylsiloxane (PDMS) was used as a mold to duplicate the pattern of the silicon hard mold. The imprinted material was transferred from the PDMS mold onto the sapphire substrate through the reversal imprinting process with roller imprinting equipment. Inductive coupled plasma (ICP) etching was then employed to fabricate hole, trapezoidal and cone structure PSS. After epitaxy and chip process, the current–voltage (I–V) and light output power for PSS LED and conventional LED were measured by a current measure unit and an integrated sphere with a calibrated power meter.
The forward voltage is almost kept identical under a 120 mA injection, it represents the PSS process may not damage the LED. Compared with conventional LED, the optical efficiencies were enhanced to 25.7 %、26.43 %、30.41 % and 28.9 % for cone profile PSS LED with 0.9 μm height、1 μm height、1.4 μm height with filling factor 83.53 percent and 1.4 μm height with filling factor 59.84 percent, respectively.
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