GeSbTe薄膜之微結構特性與太陽能電池的效率研究

Study of the microstructure and characterization for GeSbTe solar cell

朱健誠(Jian-Cheng Chu)

指導教授 ： 王錫九

國立臺北科技大學/工程學院/材料及資源工程系研究所/碩士(2012年)

https://doi.org/10.6841/NTUT.2012.00356

摘要

本實驗使用直流濺鍍法製備單層與雙層GeSbTe化合物薄膜，發現藉由雙層膜的製程可以得到結晶性質更佳的薄膜。本實驗係以直流濺鍍 15W作為薄膜沉積的濺鍍功率，第一層以濺鍍時直接加熱，或濺鍍後進行退火處理等不同的製程方式，做為本實驗比較樣品；另外，第二層GeSbTe薄膜也以直接加熱及濺鍍後進行退火處理做區別。
經由XRD的觀察發現，不論是單層膜或是經過直接加熱及退火處理的雙層膜樣品均為Ge2Sb2Te5的結構相，而且退火處理的樣品繞射圖案的峰值較明顯；且由SEM觀察可知，單層GeSbTe薄膜以及雙層GeSbTe厚度皆為60奈米，而經過兩次後熱處理後的雙層膜表面會存在許多類似多晶晶界的結構；配合UV-visible光譜儀的量測可得知這些晶界的出現使得雙層膜的穿透率有下降的趨勢；最後根據Hall量測儀的量測，以第一層直接加熱，第二層退火處理的雙層GeSbTe薄膜具有最高的載子濃度。電池元件結構分別為ITO/GST/n-Si/Cr以及ITO/GST/GST/n-Si/Cr所形成之結構。而其中直流濺鍍功率15 W之60奈米厚度的雙層GeSbTe薄膜電池元件經過兩次後熱處理皆為150℃持溫30分鐘的製程，具有0.311％的最高光電轉換效率。

關鍵字

GeSbTe硫屬化合物 ； 直流濺鍍 ； Ge2Sb2Te5 ； 穿透率 ； 太陽能電池 ； 光電轉換效率

並列摘要

This study examined that the single layer GeSbTe films and bi-layer GeSbTe films were deposited by the DC-sputtering system. The better crystalline properties were obtained by improving with bi-layer fabrication process. The film was prepared by sputtering system with dc power of 15W. The deposited films were made with single layer and bi-layer structure, heated with two conditions, direct heating and post annealing. In bi-layer films, the first layer onto substrate and second layer film are heated with various heating sequence under the above conditions.
The deposited films were confirmed by x-ray diffraction, scanning electronic microscopy, UV-visible spectrometer, and Hall measurement. The single layer GeSbTe films show less intensity of diffraction peaks. The annealing or directly heating samples both show Ge2Sb2Te5 phase through XRD. However the annealing samples have obvious diffraction peaks. The SEM figures display that the single GeSbTe film thick is 60nm, bi-layer GeSbTe films have many grain boundaries after twice annealing on surface. The UV-visible spectrum shows that the grain boundaries result in decreasing the transmittance. The electrical property of the films with bi-layer structure which was directly heating for the first layer and the post annealing for second show that bi-layer GeSbTe films through Hall measurement has the higher carrier concentration.
The cell structure is stacked ITO/GST/n-Si/Cr. The device with bi-layer GeSbTe films with two post annealing steps during 150℃ for 30 minutes has achieved 0.311％ conversion efficiency in its stack-junction solar cell.

並列關鍵字

GeSbTe chalcogenides ； DC sputter ； Ge2Sb2Te5 ； penetration ； solar cell ； efficiency

參考文獻

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