ZnO:Al透明导电膜的性能研究及其在薄膜太阳能电池上的应用
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摘要
本文采用中频脉冲磁控溅射法，通过优化ZnO：Al薄膜的制备工艺，如靶电压、本底真空度、工作气压、衬底温度、O_2／Ar，得到可用于硅薄膜太阳能电池背电极的ZnO：Al薄膜。通过膜厚、薄膜电阻率、霍尔迁移率、载流子浓度、光透过率、光反射率、薄膜成分、XRD测量，分析薄膜性能，得到最佳的工艺参数：O_2／Ar受沉积速率的影响随各参数变化而变化无固定值，靶电压265V，温度140℃，本底真空度要尽量大，工作气压0.6Pa。
为了优化硅薄膜电池ZnO：Al／Al背反射电极的增反效果，通过理论计算和实验分析，得到反射效果最佳时的膜厚是1000。与背电极紧密接触的n—Si中，n—μc—Si的耐轰击能力较强，与背反射电极的匹配较好，所以在非晶硅电池上应用n—μc—Si可以提高背反射电极的增反效果。
在硅薄膜电池的ZnO：Al／Al背反射电极应用方面，通过减小靶电压、适当增加靶距和基片的运行速度来减小对电池的轰击，改善电池性能，通过优化实验条件，使电池的短路电流提升了3.7mA／cm~2，效率增加了2％，稳定性得到改善。
In the work, mid-frequency pulse magnetron sputtering is used to prepare ZnOrAl thin films used as the back reflector of the thin silicon films solar cells. The best techological condition was obtained by optimizing the preparing conditions, (VAr is decided by the deposition rate, target voltage:265V, gas pressure:0.6Pa, the high base vacuum is expected.
For the sake of the best reflectivity, the optimized ZnO:Al film thickness of 1000A was achieved by theories calculation and exprimental analysis. The n- c-Si, which could endure the grain bombard, was used as n-layer of the solar cell with ZnOrAl/Al back reflector well.
Many measures were adopted to decrease bombard in order to improve the solar cells propertivity, such as decreasing target voltage, increasing target distance, accelerating the movement of the substrate. By optimizing the experimental conditions, short-circuit current was increased by 3.7mA/cm2, the conversion efficiency was increased by 2%, the stability was improved.
为了优化硅薄膜电池ZnO：Al／Al背反射电极的增反效果，通过理论计算和实验分析，得到反射效果最佳时的膜厚是1000。与背电极紧密接触的n—Si中，n—μc—Si的耐轰击能力较强，与背反射电极的匹配较好，所以在非晶硅电池上应用n—μc—Si可以提高背反射电极的增反效果。
在硅薄膜电池的ZnO：Al／Al背反射电极应用方面，通过减小靶电压、适当增加靶距和基片的运行速度来减小对电池的轰击，改善电池性能，通过优化实验条件，使电池的短路电流提升了3.7mA／cm~2，效率增加了2％，稳定性得到改善。
In the work, mid-frequency pulse magnetron sputtering is used to prepare ZnOrAl thin films used as the back reflector of the thin silicon films solar cells. The best techological condition was obtained by optimizing the preparing conditions, (VAr is decided by the deposition rate, target voltage:265V, gas pressure:0.6Pa, the high base vacuum is expected.
For the sake of the best reflectivity, the optimized ZnO:Al film thickness of 1000A was achieved by theories calculation and exprimental analysis. The n- c-Si, which could endure the grain bombard, was used as n-layer of the solar cell with ZnOrAl/Al back reflector well.
Many measures were adopted to decrease bombard in order to improve the solar cells propertivity, such as decreasing target voltage, increasing target distance, accelerating the movement of the substrate. By optimizing the experimental conditions, short-circuit current was increased by 3.7mA/cm2, the conversion efficiency was increased by 2%, the stability was improved.
引文
[1] 左元淮．世界太阳电池产业的发展趋势，阳光发电论坛论文集，2002．10．
[2] 赵富鑫、魏彦章．《太阳电池及其应用》，国防工业出版社，1985．2．
[3] Christopher Eisele,Christoph E.Nebel and Martin Stutzmann.Light Trapping by Periodically Structured TCO in the Submicrometer Range.Materials Society,2000,Vol.609,A30.6.1-A30.6.6
[4] 陈治明．非晶半导体材料与器件[M]．北京：科学出版社，1991．225．
[5] Katsuya Tabuchi,Wilson Wenas,Masabiro Yoshino,et al.Optimization of ZnO Films for Amorphous Silion Solar Cell[Z].Annual Res. Report,Tokyo Ins. Of Tee. 1992.88.
[6] 付恩刚．ZnO：Al的制备工艺及其性能研究．清华大学，2003．6．30
[7] 高鸿锦，刘培正，万博泉．1998年中国液晶产业年度报告(摘要)．现代显示，1999，01：26-28
[8] Baosheng SANG, Koji DAIRIKI,Akira YAMADA,et al.High-Efficiency Amorphous Silicon Solar Cells with ZnO as From Contact.Appl.Phys, 1999,Vol.38,pp:4983-4988
[9] S.Fujikake,S.Saito,H.Sato,et al.30×40cm~2 Double-junction Tandem Cells with ZnO coated SnO_2 Transparent Electrodes.Technical Digest of the International PVSEC-5,1990,623-625
[10] L.B.Jonsson,T.Nyberg, I.Katardjiev, S.Berg.Frequency response in pulsed DC reactive sputtering process. Thin Solid Films, 2000, 365: 43-48
[11] U.Krause,M.List,H.Fuchs.Requirements of Power Supply Parameters for High-Power Pulsed Magnetron Sputtering. Thin Solid Films,2001,392:196-200
[12] Chang J.F.,Wang H.L.,Hon M.H..Studying of transparent conductive ZnO:Al thin films by RF reactive magnetron sputtering.Journal of Crystal Growth,2000,211:93-97
[13] K.Ellmer, R.Wendt.D,c. and R.f.(Reactive) Magnetron Sputtering of ZnO:AI Films from Metallic and Ceramic Targets:a Comparative Study.Surface and Coatings Technology, 1997,93:21-26
[14] 叶志镇，陈汉鸿，刘榕，等．直流磁控溅射ZnO薄膜的结构和室温PL谱．半导体学报，2001，第八期，Vol．22：1015-1018
[15] A.Yamada, W.W.Wenas,M.Konagal,et al.Textured ZnO Films with the In-plane C-axis Grown by MOCVD.Technical Digest of the International PVSEC-5,1990:103
[16] 马谨，计峰，马洪磊，等．蒸发制备ZnO薄膜的结构及光学电学特性的研究．太阳能学报，1995，第二期，Vol．16：181-184
[17] 薛俊明，王雅欣，王凯杰．用中频脉冲电源溅射ZnO薄膜时脉冲参数对溅射电压的影响．见：严陆光，崔容强．21世纪太阳能新技术．上海交通大学出版社：张天薇，2003．111-113
[18] 徐彭寿，孙玉明，施朝淑，等．ZnO及其缺陷的电子结构．中国科学(A辑)，2001，第4期，Vol．31：358-365
[19] A.Van der Drift.Evolution Selection.Philips Res.Repts 22,1967,(267-268):626-631
[20] Zhang D.H.,Yang T.L.,Ma J.,et aloPreparation of Transparent Conducting ZnO:Al Films on Polymer
Substrates by r.f. Magnetron Sputtering.Applied Surface Science,2000,158:43-48
[21] R.Groenen,P.M.Sommeling,J.L.Linden,et al.Surface Textured ZnO Films for Thin Film Solar Cell Application by Expanding Thermal Plasma CVD.Thin Solid Films,2001,392:226-230
[22] B.Rech, S.Wieder, C.Beneking,et al.Texture Etched ZnO:Al Films as Front Contact and Back Reflector in Amorphous Silicon P-I-N and N-I-P Solar Cells.26th PVSC, 1997,Sept.30-Oct.3,619-622
[23] Katsuhiko Hayashi,Masataka Kondo,Atsuo Ishikawa, et al.ZnO/Ag Sputtering Deposition on a-Si Solar Cells.First WCPEC, 1994,Dec.5-9,674-677
[24] A.Banerjee,K.Hoffman,X.Xu,et al.Back Reflector Texture and Stability Issues in High Efficiency Multijunction Amorphous Silicon Alloy Solar Cells.First WCPEC, 1994,Dec.5-9,539-542
[25] Steven S.Hegedus, Wayne A,Buchanan,Erten Eser.Improving Performance of Superstrate p-i-n a-Si Solar Cells by Optimization of n/TCO/METAL Back Contacts.26th PVSC, 1997,Sept.30-Oct.3,603-606
[26] Ruhi KAPLAN,Bengu KAPLAN.Effects of the Back Reflector on the Optical Enhancement Factor and Quantum Efficiency of a-Si:H p-i-n Solar Cells.Turk J Phys,2002,26:363-368
[27] 孙以材．半导体测试技术．北京：冶金工业出版社，1984，444-447
[28] 孙以材．半导体测试技术．北京：冶金工业出版社，1984，133-148
[29] 孙以材．半导体测试技术．北京：冶金工业出版社，1984，353-364
[30] 吴正龙．XPS在测量薄膜样品中的应用—一种非破坏性XPS深度剖析测量．现代仪器使用与维修，1998，第三期，41-43
[31] 张圈世，师全林，包敏．高压X光机发射谱的测量与研究．光谱实验室，1999，Vol．16：405-407
[32] L.B. Jonsson, T. Nyberg, I. Katardjiev, et al. Frequency response in pulsed DC reactive sputtering process. Thin Solid Films, 365(2000)43-48
[33] 胡炳森，常天海，王斌。反应直流磁控溅射放电的电流—电压特性。1990
[34] Zhang D. H., Adsorption and Oesorption of Oxygen on the Surface of Polycrystalline ZnO Films Deposited by r.f. Sputtering. 物理化学学报，1995, volume 11: 791-795
[35] Baosheng Sang, Seiichi Suzuki, Akira Yamada, et al. Growth of Low-Resistive Textured ZnC Films by Atomic Layer Deposition and Their Application to a-Si Solar Ceils. 14th EUROPEAN PHOTOVOLTAIC SOLAR ENERGY CONFERENCE, 30 JUNE-4 JULY 1997,613-616
[36] D.Peros,M.Wagner, M.Scholz, et al.Interface Degradation in a-Si:H Solar Modules. 14th EUROPEAN PHOTOVOLTAIC SOLAR ENERGY CONFERENCE, 30 JUNE-4 JULY 1997,525-528
[37] Hstiebig,J.Zimmer, ESiebke,et al.Investigation of Voc in a-Si:H Based Solar Cells.14th EUROPEAN PHOTOVOLTAIC SOLAR ENERGY CONFERENCE,30 JUNE-4 JULY 1997,554-557
[38] C. Privato,M.L.Addonizio,S.Avagliano,T.Fasolino,et al.Low Cost Manufacturing Technology of Large Area, Single and Tandem Junction a-Si Modules with High Efficiency. 14th EUROPEAN PHOTOVOLTAIC SOLAR ENERGY CONFERENCE, 30 JUNE-4 JULY 1997,562-565
[39] E.Terzini,A.Rubino,R.De Rosa, et al.Relevant Process Steps for the Achievement of High Efficiency Amorphous Silicon p-i-n/p-i-n Solar Cells. 14th EUROPEAN PHOTOVOLTAIC SOLAR ENERGY CONFERENCE, 30 JUNE-4 JULY 1997,570-573
[40] B.Rech,C.Beneking, S.Wieder, et al.Initial and Stabilized Open-circuit Voltage of a-Si:H Solar Cells:a Discussion on the Basis of Dark Ⅰ-Ⅴ Curves. 14th EUROPEAN PHOTOVOLTAIC SOLAR ENERGY CONFERENCE, 30 JUNE-4 JULY 1997,574-577
[41] Y.Hishikawa, T.Kinoshita,M.Shima, et aI.OPTICAL CONFINEMENT AND OPTICAL LOSS IN HIGH-EFFICIENCY a-Si SOLAR CELLS.26th PVSC,Sept.30-Oct.3,1997,615-618
[2] 赵富鑫、魏彦章．《太阳电池及其应用》，国防工业出版社，1985．2．
[3] Christopher Eisele,Christoph E.Nebel and Martin Stutzmann.Light Trapping by Periodically Structured TCO in the Submicrometer Range.Materials Society,2000,Vol.609,A30.6.1-A30.6.6
[4] 陈治明．非晶半导体材料与器件[M]．北京：科学出版社，1991．225．
[5] Katsuya Tabuchi,Wilson Wenas,Masabiro Yoshino,et al.Optimization of ZnO Films for Amorphous Silion Solar Cell[Z].Annual Res. Report,Tokyo Ins. Of Tee. 1992.88.
[6] 付恩刚．ZnO：Al的制备工艺及其性能研究．清华大学，2003．6．30
[7] 高鸿锦，刘培正，万博泉．1998年中国液晶产业年度报告(摘要)．现代显示，1999，01：26-28
[8] Baosheng SANG, Koji DAIRIKI,Akira YAMADA,et al.High-Efficiency Amorphous Silicon Solar Cells with ZnO as From Contact.Appl.Phys, 1999,Vol.38,pp:4983-4988
[9] S.Fujikake,S.Saito,H.Sato,et al.30×40cm~2 Double-junction Tandem Cells with ZnO coated SnO_2 Transparent Electrodes.Technical Digest of the International PVSEC-5,1990,623-625
[10] L.B.Jonsson,T.Nyberg, I.Katardjiev, S.Berg.Frequency response in pulsed DC reactive sputtering process. Thin Solid Films, 2000, 365: 43-48
[11] U.Krause,M.List,H.Fuchs.Requirements of Power Supply Parameters for High-Power Pulsed Magnetron Sputtering. Thin Solid Films,2001,392:196-200
[12] Chang J.F.,Wang H.L.,Hon M.H..Studying of transparent conductive ZnO:Al thin films by RF reactive magnetron sputtering.Journal of Crystal Growth,2000,211:93-97
[13] K.Ellmer, R.Wendt.D,c. and R.f.(Reactive) Magnetron Sputtering of ZnO:AI Films from Metallic and Ceramic Targets:a Comparative Study.Surface and Coatings Technology, 1997,93:21-26
[14] 叶志镇，陈汉鸿，刘榕，等．直流磁控溅射ZnO薄膜的结构和室温PL谱．半导体学报，2001，第八期，Vol．22：1015-1018
[15] A.Yamada, W.W.Wenas,M.Konagal,et al.Textured ZnO Films with the In-plane C-axis Grown by MOCVD.Technical Digest of the International PVSEC-5,1990:103
[16] 马谨，计峰，马洪磊，等．蒸发制备ZnO薄膜的结构及光学电学特性的研究．太阳能学报，1995，第二期，Vol．16：181-184
[17] 薛俊明，王雅欣，王凯杰．用中频脉冲电源溅射ZnO薄膜时脉冲参数对溅射电压的影响．见：严陆光，崔容强．21世纪太阳能新技术．上海交通大学出版社：张天薇，2003．111-113
[18] 徐彭寿，孙玉明，施朝淑，等．ZnO及其缺陷的电子结构．中国科学(A辑)，2001，第4期，Vol．31：358-365
[19] A.Van der Drift.Evolution Selection.Philips Res.Repts 22,1967,(267-268):626-631
[20] Zhang D.H.,Yang T.L.,Ma J.,et aloPreparation of Transparent Conducting ZnO:Al Films on Polymer
Substrates by r.f. Magnetron Sputtering.Applied Surface Science,2000,158:43-48
[21] R.Groenen,P.M.Sommeling,J.L.Linden,et al.Surface Textured ZnO Films for Thin Film Solar Cell Application by Expanding Thermal Plasma CVD.Thin Solid Films,2001,392:226-230
[22] B.Rech, S.Wieder, C.Beneking,et al.Texture Etched ZnO:Al Films as Front Contact and Back Reflector in Amorphous Silicon P-I-N and N-I-P Solar Cells.26th PVSC, 1997,Sept.30-Oct.3,619-622
[23] Katsuhiko Hayashi,Masataka Kondo,Atsuo Ishikawa, et al.ZnO/Ag Sputtering Deposition on a-Si Solar Cells.First WCPEC, 1994,Dec.5-9,674-677
[24] A.Banerjee,K.Hoffman,X.Xu,et al.Back Reflector Texture and Stability Issues in High Efficiency Multijunction Amorphous Silicon Alloy Solar Cells.First WCPEC, 1994,Dec.5-9,539-542
[25] Steven S.Hegedus, Wayne A,Buchanan,Erten Eser.Improving Performance of Superstrate p-i-n a-Si Solar Cells by Optimization of n/TCO/METAL Back Contacts.26th PVSC, 1997,Sept.30-Oct.3,603-606
[26] Ruhi KAPLAN,Bengu KAPLAN.Effects of the Back Reflector on the Optical Enhancement Factor and Quantum Efficiency of a-Si:H p-i-n Solar Cells.Turk J Phys,2002,26:363-368
[27] 孙以材．半导体测试技术．北京：冶金工业出版社，1984，444-447
[28] 孙以材．半导体测试技术．北京：冶金工业出版社，1984，133-148
[29] 孙以材．半导体测试技术．北京：冶金工业出版社，1984，353-364
[30] 吴正龙．XPS在测量薄膜样品中的应用—一种非破坏性XPS深度剖析测量．现代仪器使用与维修，1998，第三期，41-43
[31] 张圈世，师全林，包敏．高压X光机发射谱的测量与研究．光谱实验室，1999，Vol．16：405-407
[32] L.B. Jonsson, T. Nyberg, I. Katardjiev, et al. Frequency response in pulsed DC reactive sputtering process. Thin Solid Films, 365(2000)43-48
[33] 胡炳森，常天海，王斌。反应直流磁控溅射放电的电流—电压特性。1990
[34] Zhang D. H., Adsorption and Oesorption of Oxygen on the Surface of Polycrystalline ZnO Films Deposited by r.f. Sputtering. 物理化学学报，1995, volume 11: 791-795
[35] Baosheng Sang, Seiichi Suzuki, Akira Yamada, et al. Growth of Low-Resistive Textured ZnC Films by Atomic Layer Deposition and Their Application to a-Si Solar Ceils. 14th EUROPEAN PHOTOVOLTAIC SOLAR ENERGY CONFERENCE, 30 JUNE-4 JULY 1997,613-616
[36] D.Peros,M.Wagner, M.Scholz, et al.Interface Degradation in a-Si:H Solar Modules. 14th EUROPEAN PHOTOVOLTAIC SOLAR ENERGY CONFERENCE, 30 JUNE-4 JULY 1997,525-528
[37] Hstiebig,J.Zimmer, ESiebke,et al.Investigation of Voc in a-Si:H Based Solar Cells.14th EUROPEAN PHOTOVOLTAIC SOLAR ENERGY CONFERENCE,30 JUNE-4 JULY 1997,554-557
[38] C. Privato,M.L.Addonizio,S.Avagliano,T.Fasolino,et al.Low Cost Manufacturing Technology of Large Area, Single and Tandem Junction a-Si Modules with High Efficiency. 14th EUROPEAN PHOTOVOLTAIC SOLAR ENERGY CONFERENCE, 30 JUNE-4 JULY 1997,562-565
[39] E.Terzini,A.Rubino,R.De Rosa, et al.Relevant Process Steps for the Achievement of High Efficiency Amorphous Silicon p-i-n/p-i-n Solar Cells. 14th EUROPEAN PHOTOVOLTAIC SOLAR ENERGY CONFERENCE, 30 JUNE-4 JULY 1997,570-573
[40] B.Rech,C.Beneking, S.Wieder, et al.Initial and Stabilized Open-circuit Voltage of a-Si:H Solar Cells:a Discussion on the Basis of Dark Ⅰ-Ⅴ Curves. 14th EUROPEAN PHOTOVOLTAIC SOLAR ENERGY CONFERENCE, 30 JUNE-4 JULY 1997,574-577
[41] Y.Hishikawa, T.Kinoshita,M.Shima, et aI.OPTICAL CONFINEMENT AND OPTICAL LOSS IN HIGH-EFFICIENCY a-Si SOLAR CELLS.26th PVSC,Sept.30-Oct.3,1997,615-618