| Summary: | 碩士 === 國立成功大學 === 微電子工程研究所碩博士班 === 96 === In this thesis, the nitride-based III-V alloys with a 12-pair MgxNy/GaN double buffer layer or pattern sapphire substrate had been grown and characterized by metal organic chemical vapor deposition system (MOCVD). Several analysis techniques, such as Hall measurement, photoluminescence (PL), X-ray diffraction (XRD), and atomic force microscopy (AFM) had also been performed to characterize the crystal quality of these epitaxial layers. The Schottky barrier diodes and metal-semiconductor-metal (MSM) photodetectors were then fabricated.
(I) GaN-based metal-semiconductor-metal ultraviolet (UV) photodetectors (PDs) with 12-pair MgxNy/GaN buffer layer and low temperature GaN (LT-GaN) buffer layer were both fabricated and characterized. It was found that we can reduce dark leakage current and enhance UV-to-visible rejection ratio both by about one order of magnitude by using a 12-pair MgxNy/GaN buffer layer. With 1 V applied bias, it was found that noise equivalent power and normalized detectivity of the PD with LT-GaN buffer layer were 2.19 10-13 W and 2.04 1012 cmHz0.5W-1, respectively, while those of the PD with 12-pair MgxNy/GaN buffer layer were 1.11 10-13 W and 6.05 1012 cmHz0.5W-1, respectively. For the Schottky diode, it was found that we could use the 12-pair MgxNy/GaN buffer layer to enhance the Shottky barrier height.
(II) GaN-based metal-semiconductor-metal ultraviolet (UV) photodetectors (PDs) prepared on patterned sapphire substrate (PSS) and conventional flat sapphire substrate were both fabricated and characterized. It was found that we can reduce dark leakage current and enhance UV-to-visible rejection ratio both by about two orders of magnitude by using PSS. With 1 V applied bias, it was found that noise equivalent power and normalized detectivity of the PD prepared on conventional flat sapphire substrate were 6.30 10-13 W and 1.06 1012 cmHz0.5W-1, respectively, while those of the PD prepared on PSS were 2.77 10-14 W and 2.42 1013 cmHz0.5W-1, respectively. For the Schottky diode, it was also found that we could use the pattered sapphire substrates to enhance the Shottky barrier height.
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