鑽石不僅具有最高的硬度、高飽和速度、較高的崩潰電壓、高能帶隙，比起傳統半導體（Si、SiC、GaAs）擁有較高的熱導率。此外，鑽石的能隙為5.47電子伏特，可以操作在較高的溫度。又鑽石的化學活性較低可以運用在惡劣的環境，並抵禦外界氣溫下降。本論文研究利用具有高沈積速率與能提供大量氫自由基特性的電場輔助熱鎢絲化學氣相低溫沈積法(Bias-assisted HWCVD, BAHWCVD)，於P型(100)矽基板上使用甲烷(CH4)與氫氣成長具非晶結構的鑽石薄膜，並以此製作奈米尖端結構高性能鈀/氧化錫/鑽石薄膜(CAIS)二極體一氧化碳感測器。利用BAHWCVD可於較低溫沈積品質較佳的鑽石薄膜。首先利用KOH 及IPA混合溶液在(100)矽基板蝕刻成奈米尖端，然後由 BAHWCVD及Sputter 分別 成長i-diamond/ p+-diamond 及 SnOx 薄膜，最後再蒸鍍鈀電極(Pd)完成感測器。吾人利用Raman量測原子間的鍵結、XRD量測薄膜結晶、SEM觀察表面結構。此外，也研究不同厚度SnOx對於元件感測特性的影響，發現在薄膜厚度為50nm時最好。並成長不同形狀的鈀電極相比較，發現方型電極對於一氧化碳有較佳的反應。
經由實驗顯示，奈米尖端結構增加感測器與氣體更多的接觸面積，相對地提昇感測電流與靈敏度。較之沒有奈米尖端者感測電流與靈敏度分別增加75倍及1.5倍。又元件在200℃，偏壓+3V及1000ppm的CO / air的環境下感測電流及靈敏度分別為112mA及 72.3%，較之已發表者的4mA及33% 分別提高26.75倍及 2.2倍。

The Catalyst/ SnOx/ i-diamond/ p+-diamond p+-silicon (CAIS) diodes with a nano tip structure are prepared by a Bias-assisted Hot-wire chemical vapor deposition (BAHWCVD) system for carbon monoxide (CO) gas sensing applications. With the added DC bias, a better quality film can be deposited under a lower temperature. We use Raman, XRD, and SEM for bond structure measurement, examination of surface morphology, analyzing crystallinity, and investigation of carbon atomic concentration with significant sp3 bonding in the film, respectively. Furthermore, effects of various patterns Pd catalyst electrode and SnO2 thicknesses on the CO sensing ability are investigated, and find the device with 50nm thick SnOx and the square Pd electrode has the highest diode sensing current and thus the highest sensitivity.
Experimental results show that with and without the nano tip structure, the diode sensing current can be enhanced up to 75 times. Besides, under 200℃, 3V forward bias, and 1000ppm CO / air ambient, the developed CAIS diode has a sensing current of 112 mA and sensitivity of 72.3%, which are respectively 75 times and 1.5 times to a reported CAIS diode diamond CO sensor prepared by a PECVD on Si substrate.

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