| Summary: | 碩士 === 國立彰化師範大學 === 光電科技研究所 === 94 === We have employed the photoluminescence (PL), surface photovoltage spectroscopy (SPS), x-ray photoelectron spectroscopy (XPS), and secondary-ion-mass spectroscopy (SIMS) measurements to study the effects of nitrogen-related defects on optical and electrical properties of heavily Mg-doped p-type GaN (p-GaN) in this study. From the PL and SPS measurements, p-GaN of (NH4)2Sx treatment suggests that the (MgGa–VN)2+ (MgGa:Ga vacancies occupied by Mg; VN:nitrogen vacancies) complexes near the p-GaN surface region were transformed into the (MgGa-SN)0 (SN:N vacancies occupied by S) complexes after (NH4)2Sx treatment, which resulted in the reduction of the ~2.8eV PL intensity and the increase of the hole concentration near the p-GaN surface region. According to the observed results from XPS and SIMS measurements, we found that the formation of more nitrogen-vacancy- related defects created near the surface by reactive ion etching technique would lead to an increase in the surface band bending, a shift of the surface Fermi level toward the conduction-band edge, the reduction of the current flow at the metal/etched p-GaN interface, and an increase in the barrier height at the metal/etched p-GaN interface. In addition, from the SIMS measurements, it is suggested that the depth of the nitrogen- deficient near-surface region resulting from the dry-etch process is about 60 nm.
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