| Summary: | 碩士 === 國立臺灣大學 === 物理研究所 === 94 === We reported an investigation of physical properties of AlGaN films grown on patterned GaN templates. It is found that with the patterned grooved-GaN templates, it is possible to manipulate the formation of the V-shape pits and optical property of AlGaN films. For a trench depth of 1.0 um, the V-shape pits can be greatly suppressed. While the GaN trench depth is up to 1.5 um, a large number of the V-shape pits present along the trench. Cathodoluminescence (CL) spectra show a strong band-edge emission around the V-shape pits. Transmission electron microscopy (TEM) data suggest that the spatial variation of intensity is due to the absence of dislocations in the sidewall of the V-shape pit. Cross-sectional CL spectrum and energy-dispersive X-ray (EDX) show compositional variation in the V-shape pits. The formation of Ga-rich domains exists in the invert apex of the V-shape pits, which induces a large density of non-radiative centers and reduces the emitted intensity. Finally, combining with the scanning Kelvin microscopy measurement, the energy band alignment of the V-shape pits is constructed for the first time, which is very useful for the understanding of physical properties of the V-shape pits.
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