| Summary: | 碩士 === 長庚大學 === 電子工程研究所 === 93 === Abstract
In this thesis, indium tin oxide (ITO) film deposited at room temperature by RF magnetron sputtering as the transparent conductive layer of InGaN Blue LED. The square micro-hole array on ITO film was fabricated, optical and electrical characteristics of the devices were also analyzed.
The ITO thin film has the lowest resistivity of 2.4×10-4 Ω-cm by post rapid thermal annealed (RTA) at 650oC in N2 ambient. In optical characteristics, the transmittance of ITO showed a high value of 98.3% by RTA at 600oC in N2 ambient. It demonstrated that ITO has excellent optoelectronic characteristics by high temperature thermal treatment. For contact between metal and p-GaN, Ni/ITO deposited on p-GaN after annealing had the lowest specific contact resistance of 1.43×10-2 Ω-cm2.
In ITO micro-hole array LED process, wet etching method was applied to etch different area and depths. From the I-V curves, it has found that the series resistance and forward voltage increased as the holes became smaller or deeper. However, the light output power of devices was enhanced with smaller or deeper holes. The extraction probability of emitting light from the device surface would increase as the device with higher density or deeper depth of the holes.
With injected current of 20 mA, the light output power was 3.54mW and the external quantum efficiency was 6.56% with arrayed square holes width of 5 m and depth of 220 nm. Compared to conventional ITO LEDs, the light output power was improved up to 28.7%.
|
|---|
