| Summary: | 碩士 === 國立臺灣大學 === 光電工程學研究所 === 88 === In this thesis, the research results of two important topics in developing GaN-based optoelectronics devices are reported. The results of laser induced p-type GaN activation are first presented. Irradiation of the second harmonic (532 nm) of a Q-switched laser has proved promising in activating Mg acceptors for p-type GaN. Because it was shown to be a non-thermal process, the activation is attributed to the photon-induced dissociation of Mg-H complexes. The dependences of hole concentration, resistivity, and mobility on laser fluence and exposure pulse number are to be discussed. Activation could be achieved within a range of laser fluence level. Second, the optical characterization results of InGaN/GaN multiple quantum well structures are reported. Based on material analysis and optical characterization, evidences of indium aggregation and phase separation in InGaN/GaN multiple quantum well samples were obtained. Various features in photoluminescence and stimulated emission spectra, such as the S-shaped photoluminescence peak wavelength and the two-peak stimulated emission spectrum, support the crucial roles of indium aggregation and phase separation in optical properties of InGaN/GaN quantum wells.
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