本論文描述在多孔碳化矽薄膜及陶瓷多晶碳化矽基板上利用金屬有機化學氣相沉積系統(MOCVD)成長多晶氮化鎵薄膜的研究。多孔碳化矽係利用快速升溫化學氣相沉積系統(RTCVD)於矽基板上成長單晶碳化矽薄膜，再利用電化學蝕刻法蝕刻出多孔狀結構；而陶瓷多晶碳化矽基板則再利用RTCVD成長一層多晶碳化矽薄膜使表面更平坦及增強結晶度。吾人利用AFM、FE-SEM及XRD等來探討此兩種材料的基本特性。再將此兩種材料製作為碳化矽金半金光感測器進一步比較此兩種材料的優劣。多孔狀碳化矽MSM光感測器的暗電流比多晶陶瓷碳化矽製作的元件小了一個數量級，但多晶陶瓷碳化矽MSM光感測器則較適合操作於高溫的操作環境下，在250°C時光增益僅衰退了30%，優於多孔碳化矽的50%。
接著在這兩種材料上成長氮化鎵薄膜，基於XRD的量測結果，兩者所成長的氮化鎵皆為多晶結構。吾人並製作出氮化鎵金半金紫外光感測器，並量測其光暗電流，發現在多孔狀碳化矽上成長的元件有較小的暗電流。因此常溫下照射366nm、6.5mW/cm2的紫外光，多孔碳化矽材料上成長的元件有較高的光增益(54304)，大於在陶瓷多晶碳化矽上成長的元件(9543)。

This thesis reports to grow GaN thin films on porous β-SiC (PSC) thin films, and ceramic poly-SiC substrates by MOCVD, respectively. The β-SiC thin films were deposited on Si substrates by RTCVD, and the PSC thin films were fabricated by electrochemical anodization method on the cubic β-SiC thin films. In addition, we grew a poly-SiC thin film on the top of the ceramic SiC substrates to smooth the ceramic surface. With the materials, the SiC photodetectors with metal-semiconductor-metal (MSM) structure were fabricated and compared. We found the leakage current of the PSC device is an order in magnitude lower than that of the ceramic poly-SiC device, however, the latter is more suitable for high temperature operating.
Furthermore, GaN thin films were grown on the substrates by MOCVD. Based on XRD analyzing, the GaN thin films on both substrates are polycrystalline structure. Finally, MSM photodetectors were grown on PSC/Si and poly-SiC/ceramic SiC, respectively. Under room temperature, and irradiation of 6.5mW/cm2 366nm UV light source, the GaN/PSC/Si photodetector biased -5V has a high optical gain of 54304, which is about 5 times over the 9543 of the GaN/poly-SiC/ceramic SiC counterpart. To our knowledge, the GaN/poly-SiC/ceramic SiC photodetector is firstly reported, and its gain of 9543 is better than some of that reported on sapphire substrate.

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