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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/68360

    Title: 成長於同調性基板的氮化鎵及氮化鋁磊晶層;Growth of GaN and AlN on Compliant Substrates
    Authors: 李明叡;Lee,Ming-Jui
    Contributors: 光電科學與工程學系
    Keywords: 氮化鎵;氮化鋁;GaN;AlN
    Date: 2015-08-21
    Issue Date: 2015-09-23 11:30:20 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 為了降低氮化物的磊晶成本,本研究以濺鍍的方式,在矽基板及多晶氮化鋁基板上形成緩衝層,以提供氮化物磊晶之同調性環境。由於矽基板與氮化鎵之間有極大的晶格與熱膨脹係數差異,使得氮化鎵的晶格應力在隨著厚度增加之後,易導致磊晶層龜裂。在矽基板上,我們以氧化鋅薄膜做為氮化鎵的磊晶緩中層,這是因為氧化鋅與氮化鎵的晶格差異只有1.8%。在研究的過程中,我們發現氧化鋅薄膜的厚度與氮化鎵的磊晶品質間有密切的關聯。
    ;In this study, we deposit buffer layers by sputtering on Si (100) and poly-AlN substrates, providing a cost-effective and compliant surface for epitaxial growth of III-nitride semiconductors. Owing to the huge mismatches in lattice constant and thermal expansion coefficient mismatch between GaN and Si substrate, the strain induced during GaN growth often leads to cracks on epi-layer’s surface, resulting in deteriorated crystal qualities. ZnO, with merely 1.8% lattice mismatch to GaN, was utilized as the buffer material to improve the crystal qualities of GaN-on-Si. By optimizing the buffer layer thickness, the undesired stain can be mitigated, deferring the formation of threading dislocations.
    The poly-AlN substrate was produced with compressed AlN powder. To smoothen the surface for epitaxial growth, the poly-AlN substrate was coated with an AlN buffer layer by RF sputtering prior to the growth. According to the results of scanning electron microscopy (SEM) and x-ray diffraction (XRD), the gas mixture of Ar/N2 and sputtered AlN films thickness play important roles in the optimization of AlN epitaxy.
    During the epitaxial growth, it is found that the AlN epilayer grown on the poly-AlN substrate exhibited pyramid-like semipolar facets. The semipolar facets have two advantageous properties for solid state lighting: i). Increasing the emission area. ii). Enhancing the radiative recombination efficiencies in the quantum wells. Moreover, pulsed-flow of NH3 precursor was adopted to enhance the lateral growth rate of AlN. The enhanced lateral growth was found effective in improving the smoothness and lattice qualities of the AlN epilayer. This study demonstrates an alternative route for the growth of ultraviolet light emitting diodes.
    Appears in Collections:[光電科學研究所] 博碩士論文

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