| Summary: | 碩士 === 逢甲大學 === 產業研發碩士班 === 97 === This research studies the gallium nitride (GaN) layer of group III-V semiconductor materials on C-plane (0001) sapphire substrate as a light emitting film by the epitaxial growth technique using metal-organic chemical vapor deposition instrumentation (MOCVD). Three different surface-roughened technologies are applied, the first is for depositing an epitaxial layer with a roughened surface at relatively low temperature under 800℃, the second is for wet etching an ITO film and the third grows zinc oxide (ZnO) nanorods on an ITO surface by the aqueous solution method. The rough textures of the ITO surface were characterized by a field emission scanning electron microscopy (FESEM) and an atomic force microscopy (AFM). The root-mean-square values (RMS) of the roughness variation of an ITO layer increased from 9.67 to 51.13 nm that make output light intensity of the GaN-LED variation from 65 to 113 mcd driving by an input current of 20 mA. The experimental results indicate that the GaN-LED after roughening surface can increase 73.8% light intensity efficiently. Also, the epitaxial layer roughening technology can promote the light extraction efficiency better than the ITO surface roughening technology. The GaN-LED on the roughened wafer by wet etching, increases light emitting intensity about 3.8% and the devices use ZnO nanorods to a rough ITO surface that can increase light intensity 31.7%. The results concluded that the roughness technique of ZnO nanorods is the best method to effective extract light intensity efficiently.
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