硒化銦與銅銦鎵硒成長與特性之研究The; growth and characterization of In2Se3 and Cu(In,Ga)Se2

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/6887

Title:	硒化銦與銅銦鎵硒成長與特性之研究The;growth and characterization of In2Se3 and Cu(In,Ga)Se2
Authors:	張國仁;Kuo-Jen Chang
Contributors:	光電科學研究所
Keywords:	銅銦鎵硒;太陽能電池;硒化銦;Cu(In;Ga)Se2;solar cells;In2Se3
Date:	2007-07-03
Issue Date:	2009-09-22 10:31:14 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	薄膜太陽能電池由於其在成本上的優勢，包括材料的節省、製程簡化、元件製作與大面積生產等特點，相對於傳統矽晶太陽能電池具有較大的潛能成為下一代太陽電池的主流。銅銦鎵硒(Cu(In,Ga)Se2，CIGS)在薄膜太陽能電池的發展中佔有極重要的地位，在Mo/CIGS/IS/ZnO電池結構中，使用硒化銦(In2Se3)薄膜做為緩衝層，而In2Se3薄膜在電池效率的增進上，扮演重要的角色。我們提出一種以雙前驅物(precursor)有機金屬氣相磊晶(Metal organic chemical vapor deposition, MOCVD)成長，將單相γ-In2Se3薄膜製備於矽基板上的方法，所用的前驅物包括TMI與H2Se，針對這兩種前驅物的流量可以獨立調整，以獲得不同的VI/III比。另外，在長晶過程中，我們亦使用了AlN及低溫生長之IS層兩種不同的緩衝層，有效改善了In2Se3薄膜的品質。In2Se3薄膜的晶體結構以XRD加以分析，結果顯示在成長溫度介於350°C與 450°C之間時，In2Se3薄膜為單相的γ-In2Se3，結構為缺陷型Wurtzite結構，同時，In2Se3薄膜的光激發螢光光譜在20K的低溫條件下，放射出明顯的激子幅射，光子能量為2.14 eV，而γ-In2Se3在常溫下之能隙預估值為1.93 eV。除了作為CIGS太陽能電池的緩衝層外，硒化銦在光電元件的製作上有很大的潛力，另外一個重要的應用是在製作相變化的儲存媒體。我們同時亦提出了一種成長CIS/CIGS薄膜的方法，同樣使用MOCVD成長方式，針對In、Ga與Se元素，分別使用TMI、TEG與H2Se為前驅物，基板則使用表面鍍銅之鈉玻璃基板，銅薄膜在反應腔中與有機氣體源反應而生成CIS/CIGS薄膜，所生長的CIS/CIGS薄膜以X光繞射法(X-ray Diffraction, XRD)加以分析，結果顯示晶體結構為黃銅礦(Chalcopyrite)結構，CIS/CIGS薄膜的能隙由於長晶條件的不同，可從0.6 eV到1.4 eV之間加以調整，此技術在未來可使用於堆疊式CIS/CIGS太陽能電池，並可能將光電轉換效率提昇至25%以上。在本論文中，我們發展了新的方法成長In2Se3與CIS/CIGS薄膜，並以MOCVD方法成功的生長了高品質的In2Se3與CIS/CIGS薄膜。因此，對於製作CIGS薄膜太陽能電池及相關的元件，均可使用MOCVD成長方法，開發單一製程技術，以降低製程轉換之影響，達到增進元件品質與效能的目的。Thin-film solar cells have the potential for substantial cost advantage versus traditional wafer-based crystalline silicon because of factors such as lower material use, fewer processing steps, and simpler device processing and manufacturing technology for large-area modules and arrays. Copper indium gallium selenide (CuIn(1-x)GaxSe2, CIGS) has attracted much attentions for its applications in thin film solar cells. Indium selenide (In2Se3) thin film has been used in Mo/CIS/In2Se3/ZnO solar cell fabrication as a buffer layer and it plays an important role in improving efficiency. We propose a method to prepare single-phase γ-In2Se3 films by using MOCVD with dual-source precursors, trimethylindium (TMI) and hydrogen selenide (H2Se), to deposit on silicon substrates. The flow rate of these two precursors could be adjusted individually to obtain desired VI/III ratio. Furthermore, the AlN and low temperature In2Se3 layers are used as buffer layer during the growth process, respectively. The crystal qualities of In2Se3 films are much improved by introducing buffer layers. The crystal structure of the γ-In2Se3 films was determined by X-ray diffraction (XRD). It is found that the films are single-phase γ-In2Se3 with defect Wurtzite structure when the growth temperatures are between 350°C to 450°C. The single-phase γ-In2Se3 films that we obtained have strong exciton emissions of 2.14 eV at 20 K. The band gap of single-phase γ-In2Se3 at room temperature is estimated at 1.93 eV. Besides the buffer layer used in CIGS-based solar cells, indium selenide also has potential applications in optoelectronic device fabrications. Another interesting application of indium selenide is in phase-change recording medium. We also propose a method to prepare CIS/CIGS films by using MOCVD with Cu/Mo-coated soda-lime glass substrates. The precursors of In, Ga and Se are TMI, triethylgallium (TEG) and H2Se, respectively. The copper films react with precursors to form CIS/CIGS films. The structure of CIS/CIGS films was determined by XRD. It is found that the films are at single chalcopyrite phase. The optical bandgap of CIS/CIGS films could be adjusted from 0.6 eV to 1.4 eV by changing the growth conditions. Therefore, the tandem cell of CIGS-based solar cells can be fabricated by using this technique and may improve the conversion efficiency over 25% in the future. In this thesis, we demonstrate new techniques of growing In2Se3 and CIS/CIGS films. The high quality In2Se3 buffer layers and CIS/CIGS films have been successfully prepared by using MOCVD methods. Thus, the development of CIGS-based solar cells and related devices can easily be achieved by using MOCVD technique with a single in-line process.
Appears in Collections:	[Graduate Institute of Optics and Photonics] Electronic Thesis & Dissertation

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