P型导电SnO_2基薄膜及其同质/异质结的研究
|
摘要
透明导电氧化物(TCO)薄膜的p型掺杂是目前半导体材料领域研究热点之一,缺乏光电性能良好的p型TCO薄膜严重阻碍了透明电子器件的发展。本论文报告具有优异光电特性的p-SnO2透明导电薄膜及其相应的SnO2基同质和异质结的制备、结构与性能。主要结果与创新点如下：
(1)在石英玻璃上制备了SnO2：Sb(ATO)薄膜并研究了热处理温度对导电类型和性能的影响。热处理温度对n、p型转化有很大影响,温度太低Sb难以进入Sn的取代位,温度过高导致5价Sb的形成,973K为最佳,空穴浓度最高达到5.83×1019cm-3,薄膜晶化度较高；可见光透过率达80%以上。
(2)在单晶硅上制备了SnO2：Sb薄膜并研究了基片温度对其导电类型和性能的影响。基片温度显著影响n、p型转化和p型导电的性能。随着基片温度升高,薄膜中颗粒形状由圆球形到类似锥形体,再变成类似纳米棒,晶格更完整和有规律,减少了晶界散射,形成性能优异的p型导电薄膜。523K时,薄膜p型导电性能最佳,空穴浓度高达1.64×1020cm-3,迁移率达8.33cm2V-1s-1；薄膜晶化程度最高,晶粒呈纳米棒状,直径约为50nm,并且沿着(101)面方向生长。
(3)在石英玻璃基片上沉积Sn02：Zn薄膜或三明治结构的Zn/SnO2/Zn薄膜,再经高温热处理或热扩散处理,制得p型Sn02：Zn透明导电薄膜,可见光透过率可达80%以上。但由于Zn2+属于深能级掺杂,电学性能比p型SnO2：Sb薄膜差得多。
(4)将p型SnO2薄膜结合n型和本征材料,制备了对应p-n或p-i-n同质结或异质结。单晶硅上p-n结(p-ATO/n-ATO同质结)和p-i-n结(p-ATO/i-SnO2/n-ATO与p-ATO/i-ZnO/n-ATO异质结)具有很好的整流特性,漏电流很小,反向电压很大,开路电压大于3V；石英玻璃上沉积的p-n结(p-ATO/n-ATO和p-SnO2：Zn/n-ATO)也具有整流的I-V曲线特性,但存在较小的漏电流,反向电压较小,开路电压小于3V,紫外可见光范围的平均透过率达到85%,实现了真正透明的p-n结器件。
As transparent conductive oxide (TCO) thin films, p-type doped semiconductor material is widely researched in recent years, lack of good p-TCO thin films in optoelectronic properties is the main problem for its application in electronic devices. This dissertation presents the preparation, structure and properties of a new type transparent p-SnO2 thin films and SnO2-based homogeneous and heterogeneous junction which have good photo-electrical performances. The main results and conclusions are as follows.
(1) Sb-doped SnO2 (ATO) thin films were deposited on quartz glass substrates and the effects of annealing temperature on p-type conducting and performance were discussed. The results indicated that the annealing temperature was critical to prepare such p-type conducting ATO films. It was found that 973K is the optimum annealing temperature to get p-ATO films with highest hole concentration (5.83×1019cm-3). If the temperature is too low, it is difficult that Sn ion is replaced by Sb; whereas Sb3+ is oxidized to Sb5+ under high temperature. In addition, the average transmittance of films in visible region is high as 80%.
(2) Sb-doped SnO2 thin films were deposited on single crystal silicon substrate and the effects of substrate temperature on p-type conducting and performance were studied. The results indicated that substrate temperature was critical to prepare p-ATO films. As the substrate temperature increases, the nano-particles in the films change their morphology from sphere-type to cone-like, and last to nanorod-array-like, the lattice of crystals becomes perfect, which decreases the grain boundary scattering and results in good performance of p-type conducting. It was found that 523K is the optimum substrate temperature to get p-ATO films with highest hole concentration (1.64×1020cm-3) and mobility (8.33cm2V-1s-1). At 523K, the thin-films are highly crystallized with nanorod-array-like structure, optimum grain size (about 50 nm in radius of the rods) and (101) plane orientation.
(3) p-type SnO2:Zn thin films were prepared by depositing Zn-doped SnO2 thin films or sandwich structure Zn/SnO2/Zn films on quartz glass substrates following heating-treatment or thermal diffusion process, and their visible light transmittance is higher than 80%. However, p-type conductivity is much smaller than thsoe of SnO2:Sb thin films, due to Zn doping in SnO2 belongs to deep-level doping.
(4) p-n and p-i-n homojunctions or heterojunctions were assembled using the above prepared p-SnO2 and other n-type and intrinsic materials. The results show that p-n (p-ATO/n-ATO) and p-i-n (p-ATO/i-SnO2/n-ATO and p-ATO/i-ZnO/n-ATO) homojunctions or heterojunctions deposited on single crystal Si substrate have very good rectification properties, small leakage currents, large backward breakdown voltages and open circuit voltages of>3V; the pn junctions (p-ATO/n-ATO and p-SnO2:Zn/n-ATO) deposited on the quartz glass substrates have also the rectification characteristics in IV curves, with small leakage currents, smaller backward breakdown voltages and open-circuit voltage smaller than 3V. The pn junctions on quartz glass substrates are transparent in all the visible region and the average transmittance of 85% was achieved.
(1)在石英玻璃上制备了SnO2：Sb(ATO)薄膜并研究了热处理温度对导电类型和性能的影响。热处理温度对n、p型转化有很大影响,温度太低Sb难以进入Sn的取代位,温度过高导致5价Sb的形成,973K为最佳,空穴浓度最高达到5.83×1019cm-3,薄膜晶化度较高；可见光透过率达80%以上。
(2)在单晶硅上制备了SnO2：Sb薄膜并研究了基片温度对其导电类型和性能的影响。基片温度显著影响n、p型转化和p型导电的性能。随着基片温度升高,薄膜中颗粒形状由圆球形到类似锥形体,再变成类似纳米棒,晶格更完整和有规律,减少了晶界散射,形成性能优异的p型导电薄膜。523K时,薄膜p型导电性能最佳,空穴浓度高达1.64×1020cm-3,迁移率达8.33cm2V-1s-1；薄膜晶化程度最高,晶粒呈纳米棒状,直径约为50nm,并且沿着(101)面方向生长。
(3)在石英玻璃基片上沉积Sn02：Zn薄膜或三明治结构的Zn/SnO2/Zn薄膜,再经高温热处理或热扩散处理,制得p型Sn02：Zn透明导电薄膜,可见光透过率可达80%以上。但由于Zn2+属于深能级掺杂,电学性能比p型SnO2：Sb薄膜差得多。
(4)将p型SnO2薄膜结合n型和本征材料,制备了对应p-n或p-i-n同质结或异质结。单晶硅上p-n结(p-ATO/n-ATO同质结)和p-i-n结(p-ATO/i-SnO2/n-ATO与p-ATO/i-ZnO/n-ATO异质结)具有很好的整流特性,漏电流很小,反向电压很大,开路电压大于3V；石英玻璃上沉积的p-n结(p-ATO/n-ATO和p-SnO2：Zn/n-ATO)也具有整流的I-V曲线特性,但存在较小的漏电流,反向电压较小,开路电压小于3V,紫外可见光范围的平均透过率达到85%,实现了真正透明的p-n结器件。
As transparent conductive oxide (TCO) thin films, p-type doped semiconductor material is widely researched in recent years, lack of good p-TCO thin films in optoelectronic properties is the main problem for its application in electronic devices. This dissertation presents the preparation, structure and properties of a new type transparent p-SnO2 thin films and SnO2-based homogeneous and heterogeneous junction which have good photo-electrical performances. The main results and conclusions are as follows.
(1) Sb-doped SnO2 (ATO) thin films were deposited on quartz glass substrates and the effects of annealing temperature on p-type conducting and performance were discussed. The results indicated that the annealing temperature was critical to prepare such p-type conducting ATO films. It was found that 973K is the optimum annealing temperature to get p-ATO films with highest hole concentration (5.83×1019cm-3). If the temperature is too low, it is difficult that Sn ion is replaced by Sb; whereas Sb3+ is oxidized to Sb5+ under high temperature. In addition, the average transmittance of films in visible region is high as 80%.
(2) Sb-doped SnO2 thin films were deposited on single crystal silicon substrate and the effects of substrate temperature on p-type conducting and performance were studied. The results indicated that substrate temperature was critical to prepare p-ATO films. As the substrate temperature increases, the nano-particles in the films change their morphology from sphere-type to cone-like, and last to nanorod-array-like, the lattice of crystals becomes perfect, which decreases the grain boundary scattering and results in good performance of p-type conducting. It was found that 523K is the optimum substrate temperature to get p-ATO films with highest hole concentration (1.64×1020cm-3) and mobility (8.33cm2V-1s-1). At 523K, the thin-films are highly crystallized with nanorod-array-like structure, optimum grain size (about 50 nm in radius of the rods) and (101) plane orientation.
(3) p-type SnO2:Zn thin films were prepared by depositing Zn-doped SnO2 thin films or sandwich structure Zn/SnO2/Zn films on quartz glass substrates following heating-treatment or thermal diffusion process, and their visible light transmittance is higher than 80%. However, p-type conductivity is much smaller than thsoe of SnO2:Sb thin films, due to Zn doping in SnO2 belongs to deep-level doping.
(4) p-n and p-i-n homojunctions or heterojunctions were assembled using the above prepared p-SnO2 and other n-type and intrinsic materials. The results show that p-n (p-ATO/n-ATO) and p-i-n (p-ATO/i-SnO2/n-ATO and p-ATO/i-ZnO/n-ATO) homojunctions or heterojunctions deposited on single crystal Si substrate have very good rectification properties, small leakage currents, large backward breakdown voltages and open circuit voltages of>3V; the pn junctions (p-ATO/n-ATO and p-SnO2:Zn/n-ATO) deposited on the quartz glass substrates have also the rectification characteristics in IV curves, with small leakage currents, smaller backward breakdown voltages and open-circuit voltage smaller than 3V. The pn junctions on quartz glass substrates are transparent in all the visible region and the average transmittance of 85% was achieved.
引文
[1]Arlinghaus F J. Energy bands in stannic oxide (SnO2) [J]. J. Phys. Chem. Solids,1974(35): 931-935.
[2]Ma Jin, Wang Yuheng, Ji Feng, et al. UV-violet photoluminescence emitted from SnO2:Sb thin films at different temperature[J]. Materials Letters,2005(59):2142-2145.
[3]Ricky W, Rong Xun Wu, Li Wen Lai, et al. ZnO-on-GaN heterojunction light-emitting diode grown by vapor coolong condensation technique[J]. Applied Physics Letters,2007(91): 231113(1-3).
[4]段理,林碧霞,傅竹西.ZnO薄膜的掺杂及其结型材料的研究进展[J].物理,2003,32(1)：27-31.
[5]Tang Z K, Wong G K L, Yu P, et al. Room-temperature ultraviolet laser emission from self-assembled ZnO microcrystallite thin films[J]. Appl. Phys. Lett.,1998(72):3270-3273.
[6]Lu J G, Ye Z Z, Yuan G D, et al. Electrical characterization of ZnO-based homojunctions [J]. Appl. Phys. Lett.,2006(89):053501(1-3).
[7]Badekez K. Tranparent conducting CdO obtained by thermal oxidation of sputtered Cd films[J]. Phys,1907(22):749-752.
[8]Wang Z G, Chen Q L, et al. Metal-based transparent heat mirror for ultraviolet curing applications[J]. Applied Surface Science,2005(239):262-267.
[9]Boehme M and Charton C. Properties of ITO on PET film in dependence on the coating conditions and thermal processing[J]. Surface and Coatings Technology,2005(200): 932-935.
[10]姜辛,孙超,洪瑞江,等.透明导电氧化物薄膜[M].第一版,北京：高等教育出版社,2008：7.
[11]Advani N, Jordan A G and Kluge-Weiss P. Analytical characterization of SnO2 thin films[J]. Mater.Sci.Eng,1979(4):99-102.
[12]Maudes J S, Rodrigue T. Sprayed SnO2 films-growth-mechanism and structure characterization[J]. Thin Solid Films,1980(69):183-189.
[13]Phillips H M, Li Y, et al. Reactive pulsed laser deposition and laser inducedcrystallization of SnO2 transparent conducting thin films[J]. Appl.Phys,1996(63):347-351.
[14]Davazoglou D, et al. Optical properties of SnO2 thin films grown by atmospheric pressure chemical vapor deposition oxidizing SnCl4[J]. Thin Solid Films,1997(302):204-213.
[15]Dolbec R, Serventi AM, et al. Microstructure and physical properties of nanostrued tin oxide thin films grown by means of pulsed laser deposition[J]. Thin Solid Films,2002(419): 230-235.
[16]Liu W, Cao L L. Electronic structure of the doped SnO2[J]. Science in China,2001(44): 63-67.
[17]Zhang J R, Gao L. Synthesis of antimony-doped tin oxide (ATO) nanoparticles by the nitrate-citrate combustion method[J]. Materials Research Bulletin,2004(39):2249-2255.
[18]Elangovan E, Ramamurthi K, Studies on micro-structural and electrical properties of spray-deposited fluorine-doped tin oxide thin films from low-cost precursor[J]. Thin Solid Films,2005(476):231-236.
[19]郝喜红,许启明等.喷雾热解法制备掺氟的氧化锡透明导电膜[J].电子元件与材料,2005(24)：7-10.
[20]Kim D W, Kim D S, et al. Preparation agglomerated antimony doped tin oxide of hard agglomerates nanoparticles reaction in methanol reaction medium[J]. Materials Chemistry and Physics,2006(97):452-457.
[21]Ozgiir U, Alivov Y I, Liu C, et al. A comprehensive review of ZnO materials and devices[J]. J. Appl. Phys.,2005(98):041301-041305.
[22]Norton D P, Heo Y W, Ivill M P, et al. Chisholm, and T.Steiner, ZnO growth, doping and processing[J]. Mater. Today,2004(7):34-40.
[23]杜娟.P型透明导电氧化物薄膜的研究[D].浙江大学,博士学位论文,2006.
[24]Van de Walle C G, Neugebauer J. First-principles calculations for defects and impurities: Applications to Ⅲ-nitrides[J]. Appl.Phy.R,2004(95):3851-3879.
[25]C.H.Park, S.B.Zhang, et al, Origin of p-type doping difficulty in ZnO: The impurity perspective[J]. Phys.Rev.B,2002(66):073202-073206.
[26]Mattila T, R.M.Nieminen, Ab initio study of oxygen point defects in GaAs, GaN and AIN[J]. Phy.Rev.B,1996,(54):16676-16682.
[27]Seghier D, Gislason H P. Electrical characterization of Mg-related energy levels and the compensation mechanism in GaN:Mg[J]. Physica B,1999(273):46-49.
[28]蔡殉,王振国,透明导电薄膜材料的研发态势[J],功能材料信息,2005(2)：15-23.
[29]Hosono H, Ohta H, et al. Frontier of transparent conductive oxide thin films[J]. Vacuum, 2002(66):419-425.
[30]Kawazoe H, Yasukawa M, et al. P-type electrical conduction in transparent thin films of CuAlO2[J]. Nature,1997(389):939-942.
[31]Kawazoe H, Yanagi H, et al. Transparent p-type conducting oxides: Design and fabrication of p-n heterojunctions[J]. MRS Bulletin,2000(25):28-37.
[32]Yanagi H, Kawazoe H, et al. Chemical design and thin film preparation of p-type conductive transparent oxides[J]. Journal of Electroceramics,2000(4):407-414.
[33]Nagarajan R, Duan N, et al. p-type conductivity in the delafossite structure[J]. International Journal of Inorganic Materials,2001(3):265-270.
[34]Stauber R E, Perkins J D, et al. Thin Film Growth of Transparent p-type CuAlO2 Electrochem[J]. Solid-State Lett.1999(2):654-658.
[35]Kudo A, Yanagi H, et al. SrCu2O2:A p-type conductive oxide with wide band gap[J]. Appl. Phys. Lett,1998(73):220-224.
[36]Ohta H, Hirano M, et al. Fabrication and photoresponse of a pn-heterojunction diode composed of transparent oxide semiconducotors, p-NiO and n-ZnO[J]. Applied Physics Letters,2003(83):1029-1031.
[37]Ohta H, Kamiya M, et al. UV-detector based on pn-heterojunction diode composed of transparent oxide semiconductors p-NiO/n-ZnO[J]. Thin Solid Films,2003(445):317-321.
[38]Srikant V, Clarke D R. On the optical band gap of zinc oxide[J]. J.Appl.Phys,1998(83): 5447-5451.
[39]Agura H, Suzuki A, Matsushita T. Low resistivity transparent conducting Al-doped ZnO films prepared by pulsed laser deposition[J], Thin Solid Films,2003(445):263-267.
[40]Lee W J, Kang J, et al. Defect properties and p-type doping efficiency in phosphorus-doped ZnO[J]. Phys. Review B,2006(73):024117-024121.
[41]Hwang D K, Kin H S, et al. Study of the phtoluminescence of phosphorus-doped p-type ZnO thin films grown by radio-frequency sputtering[J]. Applied Physics Letters, 2005(86):151917(1-3).
[42]Bian J M, Li X M, et al. P-type ZnO films by monodoping of nitrogen and ZnO-based p-n homojunctions[J]. Applied Physics Letters,2004(85):4070-4072.
[43]Barnes T M, Olson K, Wolden C A. The formation and stability of p-type conductivity in nitrogen-doped zinc oxide[J]. Applied Physics Letters,2005(86):112112(1-3).
[44]Xu W Z, Ye Z Z, et al. Low-pressure MOCVD growth of p-type ZnO thin films by using NO as the dopant source[J]. J. Crystal Growth,2004(265):133-136.
[45]Bian J M, Li X M, Gao X D, et al. Deposition and electrical properties of N-In codepd p-type ZnO films by ultrasonic spray pyrolysis[J]. Applied Physics Letters,84 (2004): 541-543.
[46]徐慢,袁启华,徐建梅.SnCl4结晶水对SnO2成膜的光电性质影响功能材料[J].武汉工业大学学报,1995,26(6)：502-504.
[47]施卫,李琦.超声喷雾法制备SnO2：F薄膜及其性能表征[J].西安理工大学学报,1998,14(1)：56-60.
[48]Mehdi M, Mohagheghi B, Shokooh-Saremi M. Optical and structural properties of Li-doped SnO2 transparent conducting films deposited by the spray pyrolysis technique: a carrier-type conversion study[J]. Semicond. Sci. Technol.2004(19):764-769.
[49]Fujihara S, Sasaki C, Kimura T. et al. Effects of Li and Mg doping on microstructure and properties of sol-gel ZnO thin films, Ceramic Society,2001,21(10-11):2109-2112.
[50]陈琛,磁控溅射法制备p型透明导电二氧化锡薄膜[D].浙江大学,硕士学位论文,2006.
[51]何振杰,P型透明导电二氧化锡薄膜的制备与性能研究[D].浙江大学,硕士学位论文,2004.
[52]刘恩科,朱秉升,罗普生等,半导体物理学[M],第四版,北京：国防工业出版,2004：35-38.
[53]Huang Y X, Ji Z G, Chen C. Preparation and characterization of p-type transparent conducting tin-gallium oxide films[J]. Applied Surface Science,2007(253):4819-4822.
[54]Mohagheghi B and Shokooh-Saremi M. The influence of Al doping on the electrical, optical and structural properties of SnO2 transparent conducting films deposited by the spray pyrolysis technique[J]. J. Phys. D: Appl. Phys.2004(37):1248-1253.
[55]Jiang D E, Carter E A. First Principles assessment of ideal fracture energies of materials with mobile impurities: implications for hydrogen emdrogen embrittlement of metals[J]. Acta Materials,2004(52):48014807.
[56]Pourghazi A, Dadsetani M, Eleetronic and optical properties of BaTe, BaS from first principle[J]. Physica B:Physies of Condensed Matter,2005(370):35-45.
[57]Masahiko M, Carlo M, et al. First principles calculation study of multi-silicon doped fullerenes[J].2005(33):237-243.
[58]Saib S, Bouarissa N,High-pressure band paramaters for GaAs[J], Solid State Electronics. 2006(50):763-768.
[59]Ji Zhenguo, He Zhenjie, Song Yongliang, et al. A Novel Transparent pn+junction Based on Indium Tin Oxide[J]. Thin Solid Films,2004(460):324-326.
[60]张君,预先镀SiO2膜玻璃基片SnO2：sb薄膜的溶胶凝胶法制备及表征[D].武汉理工大学,硕士毕业论文,2005.
[61]Bernardi M L B, Soledade L W, et al. Influence of the concentration of Sb2O3 and the viscosity of the precursor solution on the electrical and optical properties of SnO2 thin films produced by the Pechini method[J]. Thin Solid Films,2002(405):228-233.
[62]方国家,王豫.脉冲准分子激光CuO-SnO2薄膜沉积及其结构分析[J].无机材料学报,1996,11(4)：653-657.
[63]罗文秀,李凤玲.几种MOCVD掺杂SnO2膜的结构、透明度与导电性[J].无机材料学报,1990,5(2)：185-188.
[64]罗文秀,任鹏程,谭忠洛.汞灯辅助MOCVDSn02薄层晶体的结构与透明导电性研究[J],功能材料,1993,24(2)：129-133.
[65]Pan S S, Li G H, Wang L B, Atomic nitrogen doping and p-type conduction in SnO2[J], Appl. Phys. Lett.,2009(95):222112(1-3).
[66]Shanthi S, Subramanan C, Kamasamy P. Growth and characterization of antimony doped tin oxide thin films[J]. Journal of Crystal Growth,1999(197):858-861.
[67]Ji Zhenguo, Zhao Lina, He Zuopeng, et al. Transparent p-type conducting indium-doped SnO2 thin films deposited by spray pyrolysis[J]. Materials Letters,2006 (60):1387-1389.
[68]刘高斌,冯庆,李丽等.P型透明导电氧化物薄膜的研究进展[J].真空科学与技术学报,2005,25(6):444-448.
[69]Chen Chen, Ji Zhenguo, Wang Chao et al. P-type tin-indium oxide films prepared by thermal oxidation of metallic InSn alloy films[J]. Materials Letters 2006(60):3096-3099.
[70]Ji Zhenguo, He Zhenjie, Song Yongliang et al. Fabrication and characterization of indium-doped p-type SnO2 thin films[J]. Journal of Crystal Growth.2003(259):282-285.
[71]Ahmed Sk F, Khan S, Ghosh P K, et al. Effect of Al doping on the conductivity type inversion and electro-optical properties of SnO2 thin films synthesized by sol-gel technique[J]. J Sol-Gel Sci Techn.2006(39):241-247.
[72]刘树林,半导体器件物理[M],第一版,电子工业出版社,2005：110-113.
[73]施敏主编,现代半导体器件物理[M],北京：科学出版社,2001：11-15.
[74]Hao X T, Ma J, Zhang D H. Analysis of the change in the carrier concentration of SnO2 thin film gas Sensors[J]. Applied Surface Science,2002,18(9):157-161.
[75]Huang J L, PanY, Chang J.Almeida.Strain-free, Spin-coated sol-gel optical film. Surface and Coatings Technology[J]. Thin Solid Films,2004,18(4):188-193.
[76]杨邦朝.薄膜物理与技术[M].成都：电子科技大学出版社,2004：228-230.
[77]徐海阳,掺杂ZnO薄膜及ZnO基异质结发光器件研究[D],中科院长春光学精密机械与物理研究院,博士毕业论文,2006.
[78]Bilgin V, Kose S, Atay F, et al. The effect of Zn concentration on some physical properties of tin oxide films obtained by ultrasonic spray pyrolysis[J]. Materials Letters,2004(58): 3686-3693.
[79]Ji ZG, Yang CX, Liu K, et al., Structural, optical and electrical properties of ZnO thin films prepared by reactive deposition[J], J. Crystal Growth,2003,253(1-4):246-251.
[80]Ji ZG, Zhao LN, He ZP, et al. Transparent p-type conducting indium-doped SnO2 thin films deposited by spray pyrolysis[J]. Materials Letters 2006(60):1387-1389.
[81]Dawar A L, Joshi J C, Semiconducting transparent thin films:Their properties and applications[J]. J. Mater. Sci.1984(19):1-6.
[82]Eager C D, Riggs W M, Davis L E, et al. Handbook of x ray photon spectroscopy, Perkin-Elmer,1978.
[83]范志新,陈玖琳,孙以材.二氧化锡薄膜的最佳掺杂含量理论表达式[J].电子器件,2001,24(2)：132-135.
[84]薄占满.Sb掺二氧化锡半导体导电机理的实验探讨[J].无机材料学报,1990,5(4)：324-330.
[85]Pan X H, Ye Z Z, Huang J Y, et al. P-type behavior in Li-doped. Zn0.9Mg0.1O thin films[J]. J. Crystal Growth,2008(310):1029-1032.
[86]Wang Y H, Ma J, Ji F, et al. Electroluminescence of SnO2/p-Si heterojunction[J]. J. Lumin. 2005(114):71-75.
[87]Ma J, Wang Y H, Ji F, et al. UV-violet photoluminescence emitted from SnO2:Sb thin films at different temperature[J]. Mater. Lett.2005(59):2142-2146.
[88]Vanheusden K, Warren W L, Seager C H, et al. Mechanisms behind green photolumine-scence in ZnO phosphor powers[J]. J. Appl. Phys.,1996(79):7983-7986.
[89]Rani S, Roy SC, Karar N, et al., Structure, Microstructure and Photoluminescence Properties of Fe Doped SnO2 [J], Thin Films Solid State Commun.,2007(141):214-216.
[90]Ji Z.G., C.X. Yang, K. Liu, et al.:Fabrication and characterization of p-type ZnO films by pyrolysis of zinc-acetate-ammonia solution[J]. J.Cryst. Growth,2003,253:239-242.
[91]Taniyasu Y, Kasu M and MakimotoT. An aluminium nitride light-emitting diode with a wavelength of 210nm nanometers[J], Nature,2006(441):325-328.
[92]吴自勤,王兵主.薄膜生长[M].北京：科学出版社,2003：262-341.
[93]冯端.固体物理学大辞典[M].北京：高等教育出版社,1995：566.
[94]余金中,王杏华.异质结构和量子结构.物理[J],2001,30(3)：171.
[95]潘金生,仝健民,田民波.材料科学基础[M].北京：清华大学出版社,2004：415.
[96]Dawar A L, Joshi J C, Semiconducting transparent thin films-Their properties and applications[J]. J. Mater. Soc.1984(19):1-23.
[97]Wei Q S, Hirota K, Tajima K, et al. Design and Synthesis of TiO2 Nanorod Assemblies and Their Application for Photovoltaic Devices[J]. Chem. Mater.2006(18):5080-5087.
[98]Shaheen S E, Brabec C J, Sariciftci N S, et al.2.5% efficient organic plastic solar cells[J]. Appl. Phys. Lett.,2001(78):841-843.
[99]Ma W L, Yang C Y, Gong X, et al. Thermally Stable, Efficient Polymer Solar Cells with Nanoscale Control of the Interpenetrating Network Morphology[J], AdV. Funct. Mater. 2005(15):1617-1622.
[100]Reyes-Reyes M, Kim K, Carroll D L. High-efficiency photovoltaic devices based on annealed poly(3-hexylthiophene) and 1-(3-methoxycarbonyl)-propyl-l-phenyl-(6,6)C61 blends[J]. Appl. Phys. Lett.,2005(87):083506(1-3).
[101]Sato H, Minami T, Takata S, et al. Transparent conducting p-type NiO thin films prepared by magnetron sputtering[J], Thin Solid Films,1993(236):27-30.
[102]Yanagi H, Ueda K, Ohta H, et al. Mechanism for Heteroepitaxial Growth of Transparent P-Type Semiconductor:LaCuOS by Reactive Solid-Phase Epitaxy[J]. Solid State Commun. 2002(121):15-18.
[103]Mandalapu L J, Yang Z, Xiu F X, et al. Homojunction photodiodes based on Sb-doped p-type ZnO for ultraviolet detection[J]. Appl. Phys. Lett.2006(88):092103(1-3).
[104]Xu W Z, Ye Z Z, Zeng Y J, et al. ZnO light-emitting diode grown by plasma-assisted metal organic chemical vapor deposition[J]. Appl. Phys. Lett.,2006(88):173506(1-3).
[105]Jayaraj M K, Draeseke A D, Tate J, et al. P-type Transparent thin films of Cu(YCa)O2[J], Thin Solid Films,2001(397):244-247.
[106]Hazra S K and Basu S. ZnO p-n junctions produced by a new route[J]. Solid-State Electron. 2005(49):1158-1162.
[107]Heo Y W, Kwon Y W, Li Y, et al. Properties of phosphorus-doped (Zn,Mg)O thin films and device structures[J]. Appl. Phys. Lett.2004(84):3474-3476.
[108]Ryu Y R, Lee T S, Leem J H, et al. Fabrication of homostructural ZnO p-n junctions and ohmic contacts to arsenic-doped p-type ZnO[J]. Appl. Phys. Lett.2003(83):4032(1-3).
[109]Hoffman R L, Wager J F, Jayaraj M K, et al. Electrical Characterization of Transparent in Heterojunction Diodes[J], J. Appl. Phys.2001(90):5763-5768.
[110]Cao Y, Miao L, Tanemura S, et al. Low resistivity p-ZnO films fabricated by sol-gel spin coating[J], Appl. Phys. Lett.2006(88):251116(1-3).
[111]Shah J M, Li Y L, Gessmann Th et al. Experimental analysis and theoretical model for anomalously high ideality factors (n＞＞2) in AlGaN/GaN p-n junction diodes[J]. J.Appl. Phys. 2003(94):2627-2632.
[112]Lu J G, Ye Z Z, Yuan G D, et al. Electrical characterization of ZnO-basedhomojunctions [J], Appl.Phys.Lett.2006(89):053501(1-3).
[2]Ma Jin, Wang Yuheng, Ji Feng, et al. UV-violet photoluminescence emitted from SnO2:Sb thin films at different temperature[J]. Materials Letters,2005(59):2142-2145.
[3]Ricky W, Rong Xun Wu, Li Wen Lai, et al. ZnO-on-GaN heterojunction light-emitting diode grown by vapor coolong condensation technique[J]. Applied Physics Letters,2007(91): 231113(1-3).
[4]段理,林碧霞,傅竹西.ZnO薄膜的掺杂及其结型材料的研究进展[J].物理,2003,32(1)：27-31.
[5]Tang Z K, Wong G K L, Yu P, et al. Room-temperature ultraviolet laser emission from self-assembled ZnO microcrystallite thin films[J]. Appl. Phys. Lett.,1998(72):3270-3273.
[6]Lu J G, Ye Z Z, Yuan G D, et al. Electrical characterization of ZnO-based homojunctions [J]. Appl. Phys. Lett.,2006(89):053501(1-3).
[7]Badekez K. Tranparent conducting CdO obtained by thermal oxidation of sputtered Cd films[J]. Phys,1907(22):749-752.
[8]Wang Z G, Chen Q L, et al. Metal-based transparent heat mirror for ultraviolet curing applications[J]. Applied Surface Science,2005(239):262-267.
[9]Boehme M and Charton C. Properties of ITO on PET film in dependence on the coating conditions and thermal processing[J]. Surface and Coatings Technology,2005(200): 932-935.
[10]姜辛,孙超,洪瑞江,等.透明导电氧化物薄膜[M].第一版,北京：高等教育出版社,2008：7.
[11]Advani N, Jordan A G and Kluge-Weiss P. Analytical characterization of SnO2 thin films[J]. Mater.Sci.Eng,1979(4):99-102.
[12]Maudes J S, Rodrigue T. Sprayed SnO2 films-growth-mechanism and structure characterization[J]. Thin Solid Films,1980(69):183-189.
[13]Phillips H M, Li Y, et al. Reactive pulsed laser deposition and laser inducedcrystallization of SnO2 transparent conducting thin films[J]. Appl.Phys,1996(63):347-351.
[14]Davazoglou D, et al. Optical properties of SnO2 thin films grown by atmospheric pressure chemical vapor deposition oxidizing SnCl4[J]. Thin Solid Films,1997(302):204-213.
[15]Dolbec R, Serventi AM, et al. Microstructure and physical properties of nanostrued tin oxide thin films grown by means of pulsed laser deposition[J]. Thin Solid Films,2002(419): 230-235.
[16]Liu W, Cao L L. Electronic structure of the doped SnO2[J]. Science in China,2001(44): 63-67.
[17]Zhang J R, Gao L. Synthesis of antimony-doped tin oxide (ATO) nanoparticles by the nitrate-citrate combustion method[J]. Materials Research Bulletin,2004(39):2249-2255.
[18]Elangovan E, Ramamurthi K, Studies on micro-structural and electrical properties of spray-deposited fluorine-doped tin oxide thin films from low-cost precursor[J]. Thin Solid Films,2005(476):231-236.
[19]郝喜红,许启明等.喷雾热解法制备掺氟的氧化锡透明导电膜[J].电子元件与材料,2005(24)：7-10.
[20]Kim D W, Kim D S, et al. Preparation agglomerated antimony doped tin oxide of hard agglomerates nanoparticles reaction in methanol reaction medium[J]. Materials Chemistry and Physics,2006(97):452-457.
[21]Ozgiir U, Alivov Y I, Liu C, et al. A comprehensive review of ZnO materials and devices[J]. J. Appl. Phys.,2005(98):041301-041305.
[22]Norton D P, Heo Y W, Ivill M P, et al. Chisholm, and T.Steiner, ZnO growth, doping and processing[J]. Mater. Today,2004(7):34-40.
[23]杜娟.P型透明导电氧化物薄膜的研究[D].浙江大学,博士学位论文,2006.
[24]Van de Walle C G, Neugebauer J. First-principles calculations for defects and impurities: Applications to Ⅲ-nitrides[J]. Appl.Phy.R,2004(95):3851-3879.
[25]C.H.Park, S.B.Zhang, et al, Origin of p-type doping difficulty in ZnO: The impurity perspective[J]. Phys.Rev.B,2002(66):073202-073206.
[26]Mattila T, R.M.Nieminen, Ab initio study of oxygen point defects in GaAs, GaN and AIN[J]. Phy.Rev.B,1996,(54):16676-16682.
[27]Seghier D, Gislason H P. Electrical characterization of Mg-related energy levels and the compensation mechanism in GaN:Mg[J]. Physica B,1999(273):46-49.
[28]蔡殉,王振国,透明导电薄膜材料的研发态势[J],功能材料信息,2005(2)：15-23.
[29]Hosono H, Ohta H, et al. Frontier of transparent conductive oxide thin films[J]. Vacuum, 2002(66):419-425.
[30]Kawazoe H, Yasukawa M, et al. P-type electrical conduction in transparent thin films of CuAlO2[J]. Nature,1997(389):939-942.
[31]Kawazoe H, Yanagi H, et al. Transparent p-type conducting oxides: Design and fabrication of p-n heterojunctions[J]. MRS Bulletin,2000(25):28-37.
[32]Yanagi H, Kawazoe H, et al. Chemical design and thin film preparation of p-type conductive transparent oxides[J]. Journal of Electroceramics,2000(4):407-414.
[33]Nagarajan R, Duan N, et al. p-type conductivity in the delafossite structure[J]. International Journal of Inorganic Materials,2001(3):265-270.
[34]Stauber R E, Perkins J D, et al. Thin Film Growth of Transparent p-type CuAlO2 Electrochem[J]. Solid-State Lett.1999(2):654-658.
[35]Kudo A, Yanagi H, et al. SrCu2O2:A p-type conductive oxide with wide band gap[J]. Appl. Phys. Lett,1998(73):220-224.
[36]Ohta H, Hirano M, et al. Fabrication and photoresponse of a pn-heterojunction diode composed of transparent oxide semiconducotors, p-NiO and n-ZnO[J]. Applied Physics Letters,2003(83):1029-1031.
[37]Ohta H, Kamiya M, et al. UV-detector based on pn-heterojunction diode composed of transparent oxide semiconductors p-NiO/n-ZnO[J]. Thin Solid Films,2003(445):317-321.
[38]Srikant V, Clarke D R. On the optical band gap of zinc oxide[J]. J.Appl.Phys,1998(83): 5447-5451.
[39]Agura H, Suzuki A, Matsushita T. Low resistivity transparent conducting Al-doped ZnO films prepared by pulsed laser deposition[J], Thin Solid Films,2003(445):263-267.
[40]Lee W J, Kang J, et al. Defect properties and p-type doping efficiency in phosphorus-doped ZnO[J]. Phys. Review B,2006(73):024117-024121.
[41]Hwang D K, Kin H S, et al. Study of the phtoluminescence of phosphorus-doped p-type ZnO thin films grown by radio-frequency sputtering[J]. Applied Physics Letters, 2005(86):151917(1-3).
[42]Bian J M, Li X M, et al. P-type ZnO films by monodoping of nitrogen and ZnO-based p-n homojunctions[J]. Applied Physics Letters,2004(85):4070-4072.
[43]Barnes T M, Olson K, Wolden C A. The formation and stability of p-type conductivity in nitrogen-doped zinc oxide[J]. Applied Physics Letters,2005(86):112112(1-3).
[44]Xu W Z, Ye Z Z, et al. Low-pressure MOCVD growth of p-type ZnO thin films by using NO as the dopant source[J]. J. Crystal Growth,2004(265):133-136.
[45]Bian J M, Li X M, Gao X D, et al. Deposition and electrical properties of N-In codepd p-type ZnO films by ultrasonic spray pyrolysis[J]. Applied Physics Letters,84 (2004): 541-543.
[46]徐慢,袁启华,徐建梅.SnCl4结晶水对SnO2成膜的光电性质影响功能材料[J].武汉工业大学学报,1995,26(6)：502-504.
[47]施卫,李琦.超声喷雾法制备SnO2：F薄膜及其性能表征[J].西安理工大学学报,1998,14(1)：56-60.
[48]Mehdi M, Mohagheghi B, Shokooh-Saremi M. Optical and structural properties of Li-doped SnO2 transparent conducting films deposited by the spray pyrolysis technique: a carrier-type conversion study[J]. Semicond. Sci. Technol.2004(19):764-769.
[49]Fujihara S, Sasaki C, Kimura T. et al. Effects of Li and Mg doping on microstructure and properties of sol-gel ZnO thin films, Ceramic Society,2001,21(10-11):2109-2112.
[50]陈琛,磁控溅射法制备p型透明导电二氧化锡薄膜[D].浙江大学,硕士学位论文,2006.
[51]何振杰,P型透明导电二氧化锡薄膜的制备与性能研究[D].浙江大学,硕士学位论文,2004.
[52]刘恩科,朱秉升,罗普生等,半导体物理学[M],第四版,北京：国防工业出版,2004：35-38.
[53]Huang Y X, Ji Z G, Chen C. Preparation and characterization of p-type transparent conducting tin-gallium oxide films[J]. Applied Surface Science,2007(253):4819-4822.
[54]Mohagheghi B and Shokooh-Saremi M. The influence of Al doping on the electrical, optical and structural properties of SnO2 transparent conducting films deposited by the spray pyrolysis technique[J]. J. Phys. D: Appl. Phys.2004(37):1248-1253.
[55]Jiang D E, Carter E A. First Principles assessment of ideal fracture energies of materials with mobile impurities: implications for hydrogen emdrogen embrittlement of metals[J]. Acta Materials,2004(52):48014807.
[56]Pourghazi A, Dadsetani M, Eleetronic and optical properties of BaTe, BaS from first principle[J]. Physica B:Physies of Condensed Matter,2005(370):35-45.
[57]Masahiko M, Carlo M, et al. First principles calculation study of multi-silicon doped fullerenes[J].2005(33):237-243.
[58]Saib S, Bouarissa N,High-pressure band paramaters for GaAs[J], Solid State Electronics. 2006(50):763-768.
[59]Ji Zhenguo, He Zhenjie, Song Yongliang, et al. A Novel Transparent pn+junction Based on Indium Tin Oxide[J]. Thin Solid Films,2004(460):324-326.
[60]张君,预先镀SiO2膜玻璃基片SnO2：sb薄膜的溶胶凝胶法制备及表征[D].武汉理工大学,硕士毕业论文,2005.
[61]Bernardi M L B, Soledade L W, et al. Influence of the concentration of Sb2O3 and the viscosity of the precursor solution on the electrical and optical properties of SnO2 thin films produced by the Pechini method[J]. Thin Solid Films,2002(405):228-233.
[62]方国家,王豫.脉冲准分子激光CuO-SnO2薄膜沉积及其结构分析[J].无机材料学报,1996,11(4)：653-657.
[63]罗文秀,李凤玲.几种MOCVD掺杂SnO2膜的结构、透明度与导电性[J].无机材料学报,1990,5(2)：185-188.
[64]罗文秀,任鹏程,谭忠洛.汞灯辅助MOCVDSn02薄层晶体的结构与透明导电性研究[J],功能材料,1993,24(2)：129-133.
[65]Pan S S, Li G H, Wang L B, Atomic nitrogen doping and p-type conduction in SnO2[J], Appl. Phys. Lett.,2009(95):222112(1-3).
[66]Shanthi S, Subramanan C, Kamasamy P. Growth and characterization of antimony doped tin oxide thin films[J]. Journal of Crystal Growth,1999(197):858-861.
[67]Ji Zhenguo, Zhao Lina, He Zuopeng, et al. Transparent p-type conducting indium-doped SnO2 thin films deposited by spray pyrolysis[J]. Materials Letters,2006 (60):1387-1389.
[68]刘高斌,冯庆,李丽等.P型透明导电氧化物薄膜的研究进展[J].真空科学与技术学报,2005,25(6):444-448.
[69]Chen Chen, Ji Zhenguo, Wang Chao et al. P-type tin-indium oxide films prepared by thermal oxidation of metallic InSn alloy films[J]. Materials Letters 2006(60):3096-3099.
[70]Ji Zhenguo, He Zhenjie, Song Yongliang et al. Fabrication and characterization of indium-doped p-type SnO2 thin films[J]. Journal of Crystal Growth.2003(259):282-285.
[71]Ahmed Sk F, Khan S, Ghosh P K, et al. Effect of Al doping on the conductivity type inversion and electro-optical properties of SnO2 thin films synthesized by sol-gel technique[J]. J Sol-Gel Sci Techn.2006(39):241-247.
[72]刘树林,半导体器件物理[M],第一版,电子工业出版社,2005：110-113.
[73]施敏主编,现代半导体器件物理[M],北京：科学出版社,2001：11-15.
[74]Hao X T, Ma J, Zhang D H. Analysis of the change in the carrier concentration of SnO2 thin film gas Sensors[J]. Applied Surface Science,2002,18(9):157-161.
[75]Huang J L, PanY, Chang J.Almeida.Strain-free, Spin-coated sol-gel optical film. Surface and Coatings Technology[J]. Thin Solid Films,2004,18(4):188-193.
[76]杨邦朝.薄膜物理与技术[M].成都：电子科技大学出版社,2004：228-230.
[77]徐海阳,掺杂ZnO薄膜及ZnO基异质结发光器件研究[D],中科院长春光学精密机械与物理研究院,博士毕业论文,2006.
[78]Bilgin V, Kose S, Atay F, et al. The effect of Zn concentration on some physical properties of tin oxide films obtained by ultrasonic spray pyrolysis[J]. Materials Letters,2004(58): 3686-3693.
[79]Ji ZG, Yang CX, Liu K, et al., Structural, optical and electrical properties of ZnO thin films prepared by reactive deposition[J], J. Crystal Growth,2003,253(1-4):246-251.
[80]Ji ZG, Zhao LN, He ZP, et al. Transparent p-type conducting indium-doped SnO2 thin films deposited by spray pyrolysis[J]. Materials Letters 2006(60):1387-1389.
[81]Dawar A L, Joshi J C, Semiconducting transparent thin films:Their properties and applications[J]. J. Mater. Sci.1984(19):1-6.
[82]Eager C D, Riggs W M, Davis L E, et al. Handbook of x ray photon spectroscopy, Perkin-Elmer,1978.
[83]范志新,陈玖琳,孙以材.二氧化锡薄膜的最佳掺杂含量理论表达式[J].电子器件,2001,24(2)：132-135.
[84]薄占满.Sb掺二氧化锡半导体导电机理的实验探讨[J].无机材料学报,1990,5(4)：324-330.
[85]Pan X H, Ye Z Z, Huang J Y, et al. P-type behavior in Li-doped. Zn0.9Mg0.1O thin films[J]. J. Crystal Growth,2008(310):1029-1032.
[86]Wang Y H, Ma J, Ji F, et al. Electroluminescence of SnO2/p-Si heterojunction[J]. J. Lumin. 2005(114):71-75.
[87]Ma J, Wang Y H, Ji F, et al. UV-violet photoluminescence emitted from SnO2:Sb thin films at different temperature[J]. Mater. Lett.2005(59):2142-2146.
[88]Vanheusden K, Warren W L, Seager C H, et al. Mechanisms behind green photolumine-scence in ZnO phosphor powers[J]. J. Appl. Phys.,1996(79):7983-7986.
[89]Rani S, Roy SC, Karar N, et al., Structure, Microstructure and Photoluminescence Properties of Fe Doped SnO2 [J], Thin Films Solid State Commun.,2007(141):214-216.
[90]Ji Z.G., C.X. Yang, K. Liu, et al.:Fabrication and characterization of p-type ZnO films by pyrolysis of zinc-acetate-ammonia solution[J]. J.Cryst. Growth,2003,253:239-242.
[91]Taniyasu Y, Kasu M and MakimotoT. An aluminium nitride light-emitting diode with a wavelength of 210nm nanometers[J], Nature,2006(441):325-328.
[92]吴自勤,王兵主.薄膜生长[M].北京：科学出版社,2003：262-341.
[93]冯端.固体物理学大辞典[M].北京：高等教育出版社,1995：566.
[94]余金中,王杏华.异质结构和量子结构.物理[J],2001,30(3)：171.
[95]潘金生,仝健民,田民波.材料科学基础[M].北京：清华大学出版社,2004：415.
[96]Dawar A L, Joshi J C, Semiconducting transparent thin films-Their properties and applications[J]. J. Mater. Soc.1984(19):1-23.
[97]Wei Q S, Hirota K, Tajima K, et al. Design and Synthesis of TiO2 Nanorod Assemblies and Their Application for Photovoltaic Devices[J]. Chem. Mater.2006(18):5080-5087.
[98]Shaheen S E, Brabec C J, Sariciftci N S, et al.2.5% efficient organic plastic solar cells[J]. Appl. Phys. Lett.,2001(78):841-843.
[99]Ma W L, Yang C Y, Gong X, et al. Thermally Stable, Efficient Polymer Solar Cells with Nanoscale Control of the Interpenetrating Network Morphology[J], AdV. Funct. Mater. 2005(15):1617-1622.
[100]Reyes-Reyes M, Kim K, Carroll D L. High-efficiency photovoltaic devices based on annealed poly(3-hexylthiophene) and 1-(3-methoxycarbonyl)-propyl-l-phenyl-(6,6)C61 blends[J]. Appl. Phys. Lett.,2005(87):083506(1-3).
[101]Sato H, Minami T, Takata S, et al. Transparent conducting p-type NiO thin films prepared by magnetron sputtering[J], Thin Solid Films,1993(236):27-30.
[102]Yanagi H, Ueda K, Ohta H, et al. Mechanism for Heteroepitaxial Growth of Transparent P-Type Semiconductor:LaCuOS by Reactive Solid-Phase Epitaxy[J]. Solid State Commun. 2002(121):15-18.
[103]Mandalapu L J, Yang Z, Xiu F X, et al. Homojunction photodiodes based on Sb-doped p-type ZnO for ultraviolet detection[J]. Appl. Phys. Lett.2006(88):092103(1-3).
[104]Xu W Z, Ye Z Z, Zeng Y J, et al. ZnO light-emitting diode grown by plasma-assisted metal organic chemical vapor deposition[J]. Appl. Phys. Lett.,2006(88):173506(1-3).
[105]Jayaraj M K, Draeseke A D, Tate J, et al. P-type Transparent thin films of Cu(YCa)O2[J], Thin Solid Films,2001(397):244-247.
[106]Hazra S K and Basu S. ZnO p-n junctions produced by a new route[J]. Solid-State Electron. 2005(49):1158-1162.
[107]Heo Y W, Kwon Y W, Li Y, et al. Properties of phosphorus-doped (Zn,Mg)O thin films and device structures[J]. Appl. Phys. Lett.2004(84):3474-3476.
[108]Ryu Y R, Lee T S, Leem J H, et al. Fabrication of homostructural ZnO p-n junctions and ohmic contacts to arsenic-doped p-type ZnO[J]. Appl. Phys. Lett.2003(83):4032(1-3).
[109]Hoffman R L, Wager J F, Jayaraj M K, et al. Electrical Characterization of Transparent in Heterojunction Diodes[J], J. Appl. Phys.2001(90):5763-5768.
[110]Cao Y, Miao L, Tanemura S, et al. Low resistivity p-ZnO films fabricated by sol-gel spin coating[J], Appl. Phys. Lett.2006(88):251116(1-3).
[111]Shah J M, Li Y L, Gessmann Th et al. Experimental analysis and theoretical model for anomalously high ideality factors (n＞＞2) in AlGaN/GaN p-n junction diodes[J]. J.Appl. Phys. 2003(94):2627-2632.
[112]Lu J G, Ye Z Z, Yuan G D, et al. Electrical characterization of ZnO-basedhomojunctions [J], Appl.Phys.Lett.2006(89):053501(1-3).