氮化鎵具備優異的電性表現已成為第三代寬能隙半導體熱門材料，由AlGaN/GaN異質結構形成之高電子遷移率電晶體已廣泛運用在手機快充與電動車電控系統。本實驗將針對氮化鎵成長在藍寶石基板上，面臨的兩大瓶頸-藍寶石基板導熱係數差導致廢熱堆積及晶格不匹配所引起的差排缺陷問題提出可行解決方法。首先，為了解決散熱問題，提出將元件與藍寶石基板進行分離轉移技術，嘗試利用石墨烯的凡得瓦爾力及凹槽型奈米級圖案藍寶石基板的低接觸面積，進行基板分離。在凹槽型奈米級圖案藍寶石基板製作上，我們透過調整陽極處理參數可製備出孔洞占比面積33.0~59.5%的陽極氧化鋁遮罩，並使用ICP-RIE轉移孔洞圖案製備27.5~45.6 %孔洞佔比的凹槽型奈米級圖案藍寶石基板。另一方面，藉由石墨烯作為緩衝層來降低氮化鎵差排缺陷密度;石墨烯以銅膜作為催化劑，通入氫氣與甲烷，在凹槽型奈米級圖案藍寶石基板的凹槽孔洞表面上可成長ID/IG = 0.4~0.5，層數約為3~5層左右之石墨烯。本研究最後在石墨烯/凹槽型奈米級圖案藍寶石基板進行氮化鎵高電子遷移率電晶體元件結構磊晶，由掃描式電子顯微鏡影像分析指出無法連續成膜，推測原因為磊晶時的高溫導致石墨烯裂解，影響了層狀氮化鎵成長。

Gallium nitride (GaN) is a promising material for development of the third-generation wide-bandgap semiconductor. Recently, the high-power semiconductor device using GaN high electron mobility transistors (HEMTs) already applied in the fast charger of mobile phone and electric power control unit of electric vehicle. In general, GaN thin films grown on sapphire substrates suffer from several bottlenecks, such as high threading dislocations (TDs) density and waste heat accumulation. In this study, a novelty substrate which prepared a graphene interlayer on a cave nanopatterned sapphire substrate (NPSS) is proposed in order to improve TDs density and waste heat accumulation of GaN based semiconductor devices. The concave NPSS is fabricated using an anodic aluminum oxide (AAO) mask with various pattern diameters and pattern densities. The dry etching process is used for pattern transfer on sapphire substrate to create various c-plane area (i.e. without concave pattern region), ranging from 28 – 46%. In addition, the copper thin films as metal catalyst is used for growth of graphene interlayer on concave NPSS. The Raman spectrum shows the peak intensity of D-band/G-band is 0.4-0.5 and full-width at half maximum of 2D-band is 50-60
cm-1 which indicated multi-layer graphene is prepared on concave NPSS. Finally, the GaN based HEMTs is grown on graphene interlayer/concave NPSS using a metal organic chemical vapor deposition system. However, the images of scanning electron microscope showed that the surface morphology of GaN HEMTs is dominated by island structure. It is believed that the sputtering aluminum nitride buffer layer is necessary grown on graphene interlayer/concave NPSS for prevention of graphene dissociation during GaN HEMTs epitaxy.

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