在本論文中，我們利用有機化學氣相沉積系統成長出具有氮化矽氮化鎵雙緩衝層的三五族氮化物材料。為了得到高品質的磊晶材料，因此成長氮化矽的參數，例如成長時所通入的二矽乙烷、成長溫度，以及成長時間等都需要被最佳化。並且我們利用一些分析設備來對我們所成長出來的磊晶品質上的分析，而分析的設備包含霍耳量測、光致發光分析、高解析度X光繞射儀、原子力顯微鏡，以及掃描式電子顯微鏡。具有這種氮化矽氮化鎵雙緩衝層的蕭基二極體和金半金光檢測器最後被製造出來並對它的元件特性做分析。
我們嘗試出來最佳成長氮化矽的條件為二矽乙烷所通入的流量為10sccm、成長溫度在550度，以及成長時間在一分鐘時可以得品質較好的磊晶材料。並且跟傳統的低溫緩衝層比較起來，這種利用氮化矽氮化鎵雙緩衝層的磊晶材料確實有達到改善磊晶品質的目標。而改善前後磊晶樣子的改善由以下幾點說明：電子遷移率由270 增加到 435 cm2/V-s、電子濃度由6.37*1017 降到 3.5*1017 cm-3、X光的半高寬由561降到456 arcsec (102面)，以及光致發光中之黃光波段與主波段的比值由0.24下降到0.13，再加上利用原子力顯微鏡和掃描式電子顯微鏡表面之比較，可發現確實加上這一層氮化矽可達到提升磊晶品質的目標，並可有效降低材料本身的一些差排和缺陷等造成磊晶品質不好的因素。
最後我們比較具有氮化矽氮化鎵雙緩衝層和一般傳統的低溫緩衝層的氮化鎵與氮化鋁鎵材料所製造出來的蕭基二極體和金半金光檢測器元件的特性。我們可以發現具有氮化矽氮化鎵雙緩衝層的元件它有比較低的暗電流、比較大的光暗電流比、比較大的紫外光對可見光比和較佳的檢測率。而且經由計算出來樣本的蕭基能障在具有氮化矽氮化鎵雙緩衝層還是比傳統的低溫緩衝層還要大。此外金半金光檢測器由於加入氮化矽改善磊晶品質的關系，因此量測出來在雜訊上的表現比傳統緩衝層還好來得好。在論文中我們也討論了一些漏電流的傳導機制，並且發現加入氮化矽後有抑制漏電流的效果，因此使得我元件的特性上得到改善。

In this thesis, the nitride-based III-V alloys with SiN/GaN double buffer layer had been grown and characterized by metal organic chemical vapor deposition system (MOCVD). In order to realize high quality epitaxial layer, the growth conditions, such as Si2H6 flow, SiN growth temperature and growth time had been optimized. Several analysis techniques, such as Hall measurement, photoluminescence (PL), X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM) had also been performed to characterize the crystal quality of these epitaxial layers. The Schottky barrier diodes and metal-semiconductor-metal (MSM) photodetectors were then fabricated and characterized with novel SiN/GaN double buffer layer.
A detail study of epitaxial growth had also been discussed. The optimal conditions to grow the SiN layer were 10sccm for Si2H6 flow, 550℃ for growth temperature, and 1min for growth time. Compare to the traditional low temperature GaN buffer, the epitaxial film with SiN/GaN double buffer layer had greatly improved. According to the Hall measurement, the electron mobility were increased from 270 to 435 cm2/V-s, and the carrier concentration were decreased from 6.37*1017 to 3.5*1017 cm-3. The FWHM in XRD (102) and the PL ratios of IYL/IBE were both decreased from 561 to 456 arcsec and 0.24 to 0.13, respectively. Furthermore, AFM and SEM images also showed that the dislocations and defects could be dramatically reduced by inserting a SiN layer.
Finally, the Schottky diode and MSM photodetectors were fabricated by using GaN and AlGaN materials with compared SiN/GaN buffer layer and LT GaN buffer layer. The related study of devices performance had also been finished. It could be found that the samples with SiN/GaN buffer layer had a lower dark current, larger photo current to dark current contrast ratio, larger UV-to-Visible rejection ratio, and better detectivity. The Schottky barrier height of the devices with SiN/GaN buffer layer calculated by Schottky diode was larger than that with LT GaN buffer layer. Moreover, the noise properties of fabricated MSM photodetectors with SiN/GaN buffer layer were lower than that with LT GaN buffer layer. This could be also attributed to that inserting a SiN buffer layer would increase the epitaxial quality and improve the devices performance. The leakage transport mechanism had also been discussed. The reduction of dislocations and defects in the surface would avoid the leakage current caused from traps assisted tunneling.

Chapter　1
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Chapter　２
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Chapter　３
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Chapter　４
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