二硒化銅銦薄膜之硫化後處理研究

Study on the post-treatment of sulfurization to the CuInSe2 thin film solar cell

孫景渙(Ching-Huan Sun)

指導教授 ： 黃景良

崑山科技大學/工程學院/機械工程研究所/碩士(2009年)

摘要

本論文是以硫化法成長CuIn(Se,S)2薄膜，此方法需先以射頻濺鍍系統成長一CuInSe2預沉積層薄膜，接著以硫化法進行硫化。製程過程除了硫化法於大氣中成長外，其餘製程皆在低真空環境採取物理氣相沉積法方式成長鍍製。本論文的研究方法是採用硫化法去改善二硒化銅銦薄膜的硒易散失之問題，二硒化銅銦薄膜以濺鍍系統進行預沉積層之鍍製，接著在一訂製的石英爐管系統中進行硫化；CuInSe2薄膜在硫分子蒸汽壓的環境下進行硫化，目的在於以硫原子去替代易散失的硒原子，使晶格表面更平整，且完成之結構也會降低介面之間的缺陷，可以提高薄膜太陽能模組的效率，增加商業化成品良率。 本實驗使用射頻功率300W、背景溫度300℃鍍製CuInSe2預沉積層，並藉由X光繞射儀得知，當製程壓力13mtorr時的主要三根繞射峰對照CuInSe2之JCPDS卡後最為接近，故用此CuInSe2參數作為硫化實驗前製之沉積層。另外在硫化部份，採取250℃、300℃、350℃三個溫度點去進行硫化步驟，且在各溫度點之間再細分為2、5、10、20、30分鐘的硫化時間，分析結果得知以硫化溫度350℃而硫化時間10分鐘可得到薄膜品質較佳的CuIn(Se,S)2薄膜。不過隨著硫化時間越久，會導致銦的散失更嚴重，使得繞射峰值強度降低，表面平整度粗糙，但可藉由調高預沉積之銦的比例來補足易散失問題。薄膜在退火熱處理過後可明顯改善薄膜成份結晶度，並可使CuIn(Se,S)2薄膜在(112)之繞射峰值更加明顯，且降低電阻率，有效地提升其對光之吸收性，有助薄膜太陽電池之效率提升。

關鍵字

CuIn(Se,S)2 ； 射頻濺鍍法 ； 硫化法 ； 退火

並列摘要

This thesis uses sulfurization method to form the CuIn(Se,S)2 film. Firstly, the RF sputtering system is used to pre-deposit a CuInSe2 layer. Secondly, the sulfurization method is applied to make the CuInSe2 layer become CuIn(Se,S)2 film. The sulfurization is the only process under the atmosphere pressure, all the rest processes are located in a low vacuum environment and the PVD (Physical Vapor Deposition) method is applied to coat the film.
The purpose of using sulfurization method to form the CuIn(Se,S)2 film is to solve the problem of Se loss. The pre-deposition CuInSe2 layer is first coated by the RF sputtering system. Then the test element is sulfurized inside a special design quartz-tube furnace. The S atom may take over the positions of loss Se atom. Its function is to make the lattice surface tighter and smoother. The resulted construction will reduce the defect of interfaces. From this, the PV transfer efficient of CIS thin film solar module will be improved and the chance of commercialization is increased.
The 300W RF sputtering power and 300℃surrounding temperature are adopted to form the pre-deposition CuInSe2 layer in our experiments. From the detection by a XRD (X-Ray Diffraction) device, it is found that the three main diffraction peaks are close to those of CuInSe2 JCPDS at the process pressure of 13mtorr. Thus this pressure parameter is adopted to form the form the CuIn(Se,S)2 film. For the sulfurization process, three sulfurization temperatures of 250℃, 300℃ and 350℃ are adopted to combine with sulfurization durations of 2, 5, 10, 20 and 30 minutes becoming 15 sulfurization combinations. It is found that the better quality of CuIn(Se,S)2 film can be obtained in situation of 350℃sulfurization temperature and 10 minutes sulfurization duration. The longer sulfurization duration will cause the loss of In atom severely and results in the intensity-decrease of three main diffraction peaks and rougher in surface. This problem can be solved by increasing the proportion of In atom. The crystallinity of film is obviously improved after the annealing heat-treatment. The (112) diffraction peak increases more obviously. The electrical resistivity is decrease as well. From this, the absorb ability of photo is modified. Thus, this developed method can improve the PV transfer efficiency of the CIS thin film solar cell.

並列關鍵字

CuIn(Se,S)2 ； RF sputtering ； sulfurization ； anneal

參考文獻

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