| Summary: | 碩士 === 國立臺灣大學 === 光電工程學研究所 === 96 === In this research, we first demonstrate superior optical quality of a-plane GaN grown on r-plane sapphire substrate based on the flow-rate modulation epitaxy (FME) technique, in which the Ga atom supply is alternatively switched on and off with continuous nitrogen supply. Based on the results of photoluminescence measurements, one can observe the better optical property of the FME-grown a-plane GaN thin film. Besides, it was shown that strain was more relaxed in the FME sample.
Then, we demonstrate the enhanced emission efficiency and reduced spectral shifts of a green InGaN/GaN quantum-well (QW) light-emitting diode epitaxial structure by using the prestrained growth technique. By adding a ~7 %-indium InGaN/GaN QW to the structure before the growth of designated emitting high-indium QWs, the growth temperature of the emitting QWs can be raised by 30 oC while keeping about the same emission wavelength around 544 nm in photoluminescence (PL). The internal quantum efficiency and room-temperature PL intensity are increased by ~167 and ~140 %, respectively.
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