| Summary: | 碩士 === 國立高雄大學 === 應用物理學系碩士班 === 100 === This thesis studies the anisotropic properties of semipolar (11-22) GaN grown on m-sapphire substrate by the one-step and two-step growth processes. The anisotropic properties were investigated by photoluminescence (PL), atomic force microscopy (AFM), field-emission electron microscopy (FE-SEM), cathodoluminescence (CL), and Raman measurements.
First, we study the semipolar (11-22) GaN grown on m-sapphire substrate by one-step growth with different buffer layers (AlN and GaN) and by complete two-step growth with GaN buffer layer. Better optical performance, smoother surface, and lower degree of polarization (DOP) were observed for samples with GaN buffer layer. The more suitable material of buffer layer for the growth of semipolar (11-22) GaN is GaN rather than AlN. The two-step growth can reduce defect density and improve sample quality.
Second, we study the anisotropic properties of semipolar (11-22) GaN grown on m-sapphire substrate with different first-step growth thicknesses and complete two-step growth. It is shown that the larger the first-step growth thickness of semipolar (11-22) GaN, the better the sample quality. Better optical performance, smoother surface, and lower degree of polarization (DOP) were observed for samples by the two-step growth process. This shows that the two-step growth can reduce defect density and improve sample quality.
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