目前成長單晶氮化鎵薄膜以有機金屬化學氣相沉積(MOCVD)及分子束磊晶(MBE)為主，有高溫以及高成本的問題，本論文將採用低溫以及低成本且可以大面積製造的高功率脈衝磁控濺鍍法(HiPIMS)取代有機金屬化學氣相沉積(MOCVD)成長氮化鎵薄膜。而用於 GaN 成長的基板材料的另一種有潛力的材料是矽(Si)。
使用矽作為成長 GaN 的基板具有許多優勢，例如:大尺寸，低成本以及在高製程溫度下的熱穩定性。但直接成長GaN於矽基板上，由於晶格常數的巨大不匹配(16.9%)，因此需要尋找適當緩衝層來提升氮化鎵薄膜品質，而氧化鋅(ZnO)與氮化鎵之晶格常數僅相差(1.8%)，因此本論文使用氧化鋅(ZnO)作為緩衝層，進而提升氮化鎵薄膜之結晶品質。
濺鍍氧化鋅緩衝層後，再進行爐管熱退火。由XRD以及SEM分析出，退火後之氧化鋅薄膜之結晶半高寬由0.201°降至0.182°，並且結晶顆粒變大，代表結晶品質提升，但表面粗糙度(RMS)也由3.59 nm提升至13.4 nm。
由SEM量測分析出，當氧化鋅緩衝層之晶粒越大，氮化鎵薄膜之晶粒也會越大。由TEM量測分析出，當氮化鎵薄膜沉積於氧化鋅緩衝層，氮化鎵之結晶方向會延著氧化鋅緩衝層之結晶方向(0002)成長。由上述之量測分析出，ZnO緩衝層之結晶品質越好，GaN薄膜之結晶品質也會隨之提升。因此本論文之未來工作必須解決ZnO緩衝層之表面粗糙度問題，進而提升氮化鎵薄膜之品質。

Metal organic chemical vapor deposition (MOCVD) is the most popular fabrication method for the crystalline GaN thin film. However, the disadvantages of MOCVD are its high process temperature and the high cost. In this study, a fabrication method high-power impulse magnetron sputtering(HiPIMS) with low-temperature and low-cost are applied to deposit GaN films.
Silicon is one of the attractive substrate materials for GaN, the deposition of thin films with the advantages of low cost and thermal stability at high growth temperatures. But due to the large lattice constant mismatch (16.9%), it is almost impossible to deposit a GaN thin film on the silicon substrate directly. A suitable buffer layer is necessary in between the GaN and the silicon substrate to improve the quality. The lattice constant difference between ZnO and GaN is only 1.8%. So ZnO was used in this research as the buffer layer to improve the crystalline quality of the GaN films.
After depositing the ZnO buffer layer, a thermal annealing process was applied. According to the XRD and SEM analysis, the FWHM of the annealed ZnO(0002) XRD spectrum was decreased from 0.201° to 0.182°, and the crystal grains became larger, indicating that the crystal quality was improved. However, the surface roughness (RMS) was also increased from 3.59 nm to 13.4 nm.
According to the SEM measurement and analysis, the larger the crystal grains of the ZnO buffer layer, the larger the crystal grains of the GaN film. According to the TEM measurement and analysis, when the GaN film was deposited on the ZnO buffer layer, the crystal direction of GaN could grow along the crystal direction (0002) of the ZnO buffer layer. Based on the above measurement and analysis, the better the crystalline quality of the ZnO buffer layer, the better the crystalline quality of the GaN thin film. Therefore, the future work of this research is to improve the surface roughness of the ZnO buffer layer after the annealing, and then it is possible to improve the quality of the GaN films.

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