- 學位論文
化學浴沉積硫化銅薄膜之氨氣感測性質
Ammonia Gas Sensing Property of Chemical Bath Deposited CuxS Films
摘要
本文使用化學浴沉積法在室溫(25oC)沉積硫化銅薄膜，有別以往使用昂貴的真空設備，因此選擇簡單且便宜的製程方法來獲得半導體薄膜。實驗中改變不同氨水量與錯合時間，並利用SEM觀察其表面與厚度變化，使用ESCA與Raman判別硫化銅的相組成，再通入不同體積的氨氣，觀察CuxS對氨氣氣體的感測特性。 實驗結果中得到，SEM表面分析在不同氨水量，在4mL、8mL、12mL氨水下沉積4小時中，得到表面顆粒隨著氨水量的增加而表面顆粒有變大之趨勢，隨著沉積時間的增加，使得顆粒間的間隙逐漸填補；由ESCA表面分析銅2p軌域下發現有兩大波峰分別為932eV、952eV，因此薄膜的化學計量比(Cu/S)趨近於2；I-V量測中得知CuxS與金是歐姆接觸且隨沉積時間的增加電阻有變小的趨勢；分別比較氨水量為4mL、8mL、12mL及沉積4小時下的氨氣感測，在氨水量12mL沉積4小時的條件下顆粒較為粗糙，顆粒間的邊界也相當的多，當氨氣(28-30%)150mL灌入27.7公升的腔體，可獲得最好的靈敏度為2.2%。 在氨水量12mL、沉積時間2小時下，改變不同錯合時間可由SEM剖面下，得知厚度並無太大差異，但觀察表面顆粒隨錯合時間有逐漸變小趨勢，經過20小時後薄膜有較為緻密。在不同錯合時間下，其試片做氨氣感測，得知在錯合時間5小時中，當氨氣(28-30%)150mL灌入27.7公升的腔體下，獲得最好的靈敏度為18.5%。
並列摘要
Copper sulfide thin films deposited at room temperature (25oC) in a chemical bath were studied for the ammonia gas sensing application. Unlike vacuum experiments using expensive equipments, chemical bath process in this study is a simple and inexpensive method to obtain semiconductor films. Under different ammonium hydroxide volume (4-12mL) as well as deposition time (2-16h) and complexing time (2.5-20h), we studied surface morphology and thickness changes by SEM, and chemical composition of copper sulfides by ESCA and Raman techniques. For gas sensing investigation, various ammonia volumes (1-150mL) were poured into a chamber with a capacity of 27.7L for understanding CuxS sensing sensitivity. The results showed the CuxS particle sizes increase with different ammonium hydroxide volume at deposition time of 4 hrs observed by SEM, moreover the gaps between particles boundaries are gradually filled corresponding to deposition time. The specimen appears two peaks of Cu-2p at 932eV and 952eV in ESCA analysis that indicate the film stoichiometry (Cu/S) is near to 2. The resistance of ohmic contact between CuxS and gold reduces with the function of deposition time detected by IV measurement. Comparing different ammonium hydroxide volume of 4mL, 8mL and 12mL and at deposition time 4hrs, the particle is coarse and the film exhibits more grain boundary at ammonia volume 12 mL. When the ammonia volumes of 150mL (28-30%) put into a sensing chamber with 27.7L volume, a better sensitivity of 2.2% was obtained. The thickness by SEM observation is not obvious difference at the condition of ammonia volume 12mL, deposition time 2hrs and different complexing time, but the particle size reduces with the function of complexing time. The film become more dense after process time of 20 hours. When the ammonia volumes of 150mL (30% concentration) put into a sensing chamber with 27.7L volume for sensing test, the best sensitivity of 18.5% was obtained at complexing time of 5 hrs.