The study of Zn doped CuInSe2 thin film by selenization of co-sputtering Cu-In-Zn alloy

[[abstract]]黃銅礦結構的銅銦鎵二硒合金是一個低成本且適合做為高效率吸收層的材料。多元共蒸鍍銅銦鎵二硒，其最高效率已可達19.9%。使用水浴法成長的硫化鎘扮演一個重要的角色，當沉積硫化鎘時，鎘會擴散到銅銦鎵二硒的表面而形成同質接面。因此，硫化鎘一直被用來當作銅銦鎵二硒的緩衝層。但鎘非常毒，所以使用硫化鎘會牽涉到處理的問題而且會污染環境。近來，有人使用物理氣相沉積摻雜鋅到銅銦鎵二硒。文中指出刻意將鋅摻雜到銅銦鎵二硒可形成同質接面。但鋅摻雜到銅銦鎵二硒的研究並不是很完全。 本研究利用硒化共濺鍍銅銦鋅合金形成n型的銅銦硒，並探討不同鋅含量的光學與電特性。因為鋅已被摻雜在銅銦先驅物，所以此方法不需要其它的製程設備進行擴散鋅的製程。從XRD圖中觀察到偏離化學計量比的試片有較多的二元相，但圖中沒有明顯的鋅化合物的相位。在SEM圖中觀察到晶粒會隨著鋅含量增加而增大。經過霍爾量測，摻雜0.3%鋅的薄膜的導電型態會從p型轉為n型。而銅銦二硒薄膜的能隙會從未摻雜鋅的0.97 eV降到有摻雜4.25%鋅的0.89 eV。[[abstract]]Chalcopyrite-structure Cu(In,Ga)Se2 (CIGS) alloys are the most promising materials for use as a low cost and high efficiency absorber layer. The highest efficiencies of 19.9% for thin-film Cu(In,Ga)Se2 (CIGS) solar cells have been faricated by the multi-source elemental co-evaporation process.A CdS buffer layer deposited by chemical bath deposition (CBD) method has long been used for CIGS cells, because the CdS layer plays important role in forming a pn-homojunction in the CIGS surface layer resulted from Cd diffusion. The use of CdS involves handling problems and environmental concerns, because Cd is highly toxic.Recently, a Zn doping into CIGS films by PVD method has been reported. It was pointed out that the Zn doping can intentionally fabricate a pn homejunction in the CIGS films.However, the doping of Zn has been fully studied. In this study, a n-type CIS film was fabricated by selenization of co-sputtering Cu-In-Zn alloy. It’s electrical and optical properties of different Zn amount are discussed . Because of Zn being doped in CuIn precursor, there are no other process equipments needed to diffuse Zn. It is observed that the XRD images of samples which deviate from stoichiometry have more binary phases, and there is no obvious Zn compound phase. The SEM images show that the grain size increases as Zn content increases. From Hall measurement, the thin film doped with 0.3% Zn will transform from p type to n type. The energy bandgap of CIS thin film will decrease from 0.97 eV of undoped Zn to 0.89 eV of 4.25% doped Zn