氧化亞銅(Cuprous oxide)為直接能隙P型半導體材料，是屬於一種非化學計量比缺陷半導體(non stoichiometric defect semiconductor)，光學能隙值約在2.1-2.5eV之間，具有低製造成本、無毒性、起始材料在自然界中含量豐富等優點，並且在可見光範圍內具有相當高的光吸收係數，因此主要的應用可用來製造太陽能電池元件。
本實驗是利用反應式直流磁控濺鍍系統成長氧化亞銅薄膜，先找出氧化亞銅結晶相範圍之沉積條件，探討改變製程參數對薄膜微結構及光電特性之影響。以製程溫度300oC沉積氧化亞銅薄膜，製備p-Cu2O / n-ITO與p-Cu2O / i-ZnO / n-ITO異質接面元件，並分析元件之I-V特性曲線。
研究結果顯示，在固定濺鍍功率為100W，製程壓力為3.3 Pa，氬氣流量為10 sccm，氧氣流量為1 sccm，並改變基板溫度由50oC至300oC之沉積範圍內，皆可得到Cu2O之結晶相。並發現薄膜在基板溫度50oC及100oC沉積氧化亞銅薄膜具有n型半導體特性，而在基板溫度150oC至300o沉積薄膜可獲得p型半導體特性。而氧化亞銅薄膜於基板溫度300oC可得到最高載子移動率為12cm2/V-s。另外發現薄膜經真空300oC退火20分鐘皆可有效的降低薄膜電阻率，可將退火前的867Ω-cm降至退火後的77Ω-cm。在p-Cu2O / n-ITO異質接面元件中因有很大的漏電流產生，使其元件類似歐姆特性，而使用p-i-n異質接面元件則可降低元件漏電流的現象，且具有較佳的整流特性曲線。

Cuprous oxide (Cu2O) is a direct band gap semiconductor with optical band gap energy of 2.0 - 2.5eV. It is a non-stoichiometric p-type semiconductor. The attractiveness of cuprous oxide as a photovoltaic materials because of its high absorption coefficient in visible regions, non-toxicity, abundantly available starting material (Cu) on the earth and low cost producibility.
In this study, the cuprous oxide films were grown by dc reactive magnetron sputtering. The first is to find the deposition conditions of Cu2O phase. The second is to research the effect of various sputtering parameters on microstructure and electrical properties. The p-Cu2O/n-ITO and p-Cu2O/i-ZnO/n-ITO heterojunction devices were prepared by magnetron sputtering. The I-V characteristic of device was measured by solar cell simulator system.
The results show that the Cu2O could be obtain at deposition conditions of DC sputtering power 100W, pressure 3.3 Pa, Ar flow rate 10 sccm, O2 flow rate 1 sccm and different substrate temperature from 50oC to 300oC. The n-type semiconductor of Cu2O films were obtained at substrate temperature 50oC and 100oC. With increasing the substrate temperature from 150 oC to 300 oC, the Cu2O films obtained were a p-type semiconductor. The mobility of 12 cm2/V-s was obtained at substrate temperature 300oC. The resistivity of Cu2O films decreased from 867 Ω-cm to 77 Ω-cm after annealing in vacuum at 300oC for 20min. The p-Cu2O/n-ITO heterojunction device exhibits large leakage current resulting in ohmic-like I-V characteristics. An i-ZnO layer was included to decreased the reverse leakage current between the p-Cu2O and n-ZnO layers. The p-Cu2O/i-ZnO/n-ITO heterojunction devices could be obtain for a rectifying characteristic.

總 目 錄
中文摘要.............................................................I
英文摘要………………………………………...…………………………………….......II
誌謝…………………………………………………………………………………….......III
總目錄……..…………………………………………………………………………........IV
圖目錄 ………………………………………………………………………...………......VI
表目錄 ……………………………………………………………………………........VIII
第一章 緒論…………………….………………………….……………………….......1
1-1 前言 ……………………………………………...……………………….........1
1-2 研究動機及目的 ………………………………………………...……….........2
第二章 基礎理論及文獻回顧…………………………………………………………......3
2-1 氧化亞銅薄膜之特性介紹…………………………...……………………….....3
2-2 電漿原理 ………………………………………...………………………….....13
2-3 濺鍍原理 ………………………………………………………...………….....14
2-4 薄膜成長原理…..…………………………………………………………….....16
第三章 實驗方法與步驟 ……………………………………………………………........22
3-1 實驗流程………………………………………………………………….........22
3-2 實驗材料………………………………………………………………….........23
3-3 實驗設備………………………………………………………………….........25
3-4 製備氧化亞銅之參數及步驟…………………………………………….........27
3-5 薄膜分析設備…………………………………………………………….........29
3-6 製備氧化亞銅薄膜異質接面元件………………..………………………….....31
第四章 結果與討論 …………………………………………………………………........33
4-1 氧氣流量對氧化亞銅薄膜特性之影響………………………………….........33
4-2 濺鍍功率對氧化亞銅薄膜特性之影響………………………………….........36
4-3 基板溫度對氧化亞銅薄膜特性之影響………………………………….........39
4-4 退火對氧化亞銅薄膜特性之影響...................................57
4-5 氧化亞銅薄膜之異質接面元件特性……………………..………………….....76
第五章 結論 …………………………………………………………………………........85
參考文獻………………………………………………………………………………........86
Publication list...................................................92


圖目錄
圖 2-1 氧化亞銅之晶體結構圖 ……………………………………………………….......4
圖 2-2 表面懸浮鍵經由氫電漿處理後之示意圖…….………………………………......8
圖 2-3 基板表面上薄膜之成核與成長示意圖 ………………………………….........18
圖 2-4 薄膜三種成長樣式 (a) Volmer-Weber樣式，(b) Frank-van
der Merwe樣式，(c) Stranski-Krastanov樣式…………………………….19
圖 2-5 濺鍍薄膜之結構區(Thorntone Zone)模型……………………….……….....21
圖 3-1 實驗流程圖 ……………………………………………………………….........22
圖 3-2 磁控濺鍍系統圖 ………………………………………………………….........26
圖 3-3 異質接面元件結構示意圖 (a) p-Cu2O/n-ITO, (b)
p-Cu2O/i-ZnO/n-ITO……………………………………..................32
圖 4-1 不同氧氣流量對氧化亞銅薄膜沉積速率之影響……………………………......34
圖 4-2 不同氧氣流量對氧化亞銅薄膜結晶結構之影響 (a) 1 sccm, (b) 2 sccm,
(c) 3 sccm .................................................35
圖 4-3 不同濺鍍功率對氧化亞銅薄膜沉積速率之影響……………………………......37
圖 4-4 不同濺鍍功率對氧化亞銅薄膜結晶結構之影響 (a) 100W, (b) 150W,
(c) 200W, (d) 250W ………………………………………………………...............................38
圖 4-5 不同基板溫度對氧化亞銅薄膜沉積速率之影響 ……………………….........40
圖 4-6 不同基板溫度對氧化亞銅薄膜結晶結構之影響 (a) 50oC,(b) 100oC,
(c) 150oC, (d) 200oC, (e) 250oC, (f) 300oC..............................................................41
圖 4-7 氧化亞銅薄膜於不同基板溫度之表面型態 (a) 50oC, (b) 100oC,
(c) 150oC, (d) 200oC, (e) 250oC, (f) 300oC …................43
圖 4-8 不同基板溫度之氧化亞銅薄膜表面AFM微觀結構(a) 50oC,(b) 100oC,
(c) 150oC, (d) 200oC, (e) 250oC, (e) 300oC .................44
圖 4-9 不同基板溫度對氧化亞銅薄膜內銅與氧原子比例之影響…….……....….....46
圖 4-10不同基板溫度對氧化亞銅薄膜光穿透率之影響..........................48
圖 4-11不同基板溫度對氧化亞銅薄膜光反射率之影響..........................49
圖 4-12不同基板溫度對氧化亞銅薄膜光吸收率之影響..........................51
圖 4-13不同基板溫度對氧化亞銅薄膜光學能隙之影響..........................52
圖 4-14不同基板溫度對氧化亞銅薄膜載子濃度與移動率之影響………………........55
圖 4-15 不同基板溫度對氧化亞銅薄膜電阻率之影響……………………............56
圖 4-16 不同退火溫度對氧化亞銅薄膜結晶結構之影響...……………………........58
圖 4-17 氧化亞銅薄膜於不同溫度真空退火20分鐘後之表面型態
(a) 100oC, (b)150oC, (c) 200oC, (d) 250oC, (e) 300oC .......59
圖 4-18 不同退火溫度對氧化亞銅薄膜載子濃度及移動率之影響…………….........61
圖 4-19 不同退火溫度對氧化亞銅薄膜電阻率之影響………………...………........62
圖 4-20 300oC退火後對氧化亞銅薄膜結晶結構之影響…...………..............63
圖 4-21 氧化亞銅薄膜於真空300oC退火20分鐘後之表面型態
(a) 50oC, (b) 100oC, (c) 150oC, (d) 200oC, (e) 250oC,
(f) 300oC ..................................................65
圖 4-22 氧化亞銅薄膜於真空300oC退火20分鐘後之AFM表面微觀結構 (a)
50oC, (b) 100oC, (c) 150oC, (d) 200oC, (e) 250oC,
(e) 300oC...................................................66
圖 4-23 300oC退火對氧化亞銅薄膜內銅與氧原子比例之影響…………............67
圖 4-24 300oC退火對氧化亞銅薄膜光穿透率之影響………...……………...…....69
圖 4-25 300oC退火對氧化亞銅薄膜光反射率之影響………...……………….......70
圖 4-26 300oC退火對氧化亞銅薄膜光吸收率之影響…………….................71
圖 4-27 300oC退火對氧化亞銅薄膜光學能隙之影響…………...................72
圖 4-28 300oC退火對氧化亞銅薄膜載子濃度及移動率之影響...................74
圖 4-29 300oC退火對氧化亞銅薄膜電阻率之影響…...……………………….......75
圖 4-30 p-Cu2O/n-ITO元件量測示意圖……………...……………..……………...77
圖 4-31 p-Cu2O/n-ITO異質接面之I-V特性曲線圖………………..………………...78
圖 4-32 p-Cu2O/n-ITO異質接面於退火後之I-V特性曲線圖………………..……...79
圖 4-33 p-Cu2O/i-ZnO/n-ITO元件量測示意圖……………………………………....82
圖 4-34 p-Cu2O/i-ZnO/n-ITO異質接面之I-V特性曲線圖………………………....83
圖 4-35 p-Cu2O/i-ZnO/n-ITO異質接面於退火後之I-V特性曲線圖………..……..84


表目錄
表 2-1 歷年來以濺鍍法製備氧化亞銅薄膜之重要文獻總覽……………………….......7
表 2-2 歷年氧化亞銅薄膜應用於太陽能電池製作之元件特性文獻總覽…………......11
表 2-3 氧化亞銅薄膜用於太陽能電池之薄膜特性文獻總覽………………………......12
表 3-1 康寧1737F玻璃特性…………………………………………….…………….....24
表 3-2 氧化亞銅薄膜製程參數表………………………………………………..........27
表 4-1 氧化亞銅薄膜應用於太陽能電池元件之研究結果比較……………………......81

參考文獻
[1] A. O. Musa, T. Akomolafe and M.J. Carter, “Production of cuprous oxide, a solar cell material, by thermal oxidation and a study of its physical and electrical properties”, Sol. Energy Mater. Sol. Cells, 51 (1998) 305-316.
[2] M. Ivill, M. E. Overberg, C. R. Abernathy, D. P. Norton, A. F. Hebard, N. Theodoropoulou and J. D. Budai, “Properties of Mn-doped Cu2O semiconducting thin films grown by pulsed-laser deposition”, Solid-State Electronics, 47 (2003) 2215-2220.
[3] L. Pan, H. Zhu, C. Fan, W. Wang, Y. Zhang and J. Q. Xiao, “Mn-doped Cu2O thin films grown by rf magnetron sputtering”, J. Appl. Phys., 97 (2005) 10D318.
[4] J. Antony, Y. Qiang, M. Faheem, D. Meyer, D. E. Mccready and M. H. Engelhard, “Ferromagnetic semiconductor nanoclusters：Co-doped Cu2O”, Appl. Phys. Lett., 90 (2007) 013106.
[5] T. J. Richardson, J. L. Slack and M. D. Rubin, “Electrochromism in copper oxide thin films”, Electrochimica Acta, 46 (2001) 2281-2284.
[6] C. Jayewardena, K. P. Hewaparakrama, D. L.A. Wijewardena and H. Guruge, “Fabrication of n-Cu2O electrodes with higher energy conversion efficiency in a photoelectrochemical cell”, Sol. Energy Mater. Sol. Cells, 56 (1998) 29-33.
[7] T. Mahalingam, J. S. P. Chitra, J. P. Chu, H. Moon, H. J. Kwon and Y. D. Kim, “Photoelertrochemical solar cell studies on electroplated cuprous oxide thin films”, J. Mater. Sci.: Mater. Electron, 17 (2006) 519-523.
[8] R. Chandra, P. Taneja and P. Ayyub, “Optical properties of transparent nanocrystalline Cu2O thin films synthesized by high pressure gas sputtering”, NanoStructured Materials, 11 (1999) 505-512.
[9] S. Ishizuka, T. Maruyama and K. Akimoto, “Thin-Film Deposition of Cu2O by Radio-Frequency Magnetron Sputtering”, Jpn. J. Appl. Phys., 39 (2000) L786-L788.
[10] S. Ghosh, D. K. Avasthi, P. Shah, V. Ganesan, A. Gupta, D. Sarangi, R. Bhattacharya and W. Assmann, “Deposition of films of different oxides of copper by RF reactive sputtering and their characterization”, Vacuum, 57 (2000) 377-385.
[11] J. F. Pierson, A. Thobor-Keck and A. Billard, “Cuprite, paramelaconite and tenorite films deposition by reactive magnetron sputtering”, Appl. Surf. Sci., 210 (2003) 359-367.
[12] A. S. Reddy, G. V. Rao, S. Uthanna and P. S. Reddy, “Influence of substrate bias voltage on the properties of magnetron sputtered Cu2O films”, Physica B, 370 (2005) 29-34.
[13] A. S. Reddy, G. V. Rao, S. Uthanna and P. S. Reddy, “Structural and optical studies on dc reactive magnetron sputtered Cu2O films”, Materials Letters, 60 (2006) 1617-1621.
[14] A. S. Reddy, P. S. Reddy, S. Uthanna, G. V. Rao and A. Klein, “Effect of substrate temperature on the physical properties of dc magnetron sputtered Cu2O films”, Phys. Stat. Sol. (a), 203 (2006) 844-853.
[15] A. S. Reddy, S. Uthanna and P. S. Reddy, “Properties of dc magnetron sputtered Cu2O films prepared at different sputtering pressure”, Appl. Surf. Sci., 253 (2007) 5287-5292.
[16] J. Li, G. Vizkelethy, P. Revesz, J. W. Mayer and K. N. Tu, “Oxidation and reduction of copper oxide thin films”, J. Appl. Phys., 69 (1991) 1020-1029.
[17] M. Lenglet, K. Kartouni, J. Machefert, J. M. Claude, P. Steinmetz, E. Beauprez, J. Heinrich and N. Celati, “Low temperature oxidation of copper：the formation of CuO”, Mater. Res. Bullet, 30 (1995) 393-403.
[18] M. O’Reilly, X. Jiang, J. T. Beechinor, S. Lynch, C. N. Dheasuna, J. C. Patterson and G. M. Crean, “Investigation of the oxidation behaviour of thin film and bulk copper”, Appl. Surf. Sci., 91 (1995) 152-156.
[19] G. Papadimitropoulos, N. Vourdas, V. Em. Vamvakas and D. Davazoglou, “Optical and structural properties of copper oxide thin films grown by oxidation of mental layers”, Thin Solid Films, 515 (2006) 2428-2432.
[20] T. Maruyama, “Copper Oxide Thin Films Prepared from Copper Dipivaloylmethanate and Oxygen by Chemical Vapor Deposition”, Jpn. J. Appl. Phys., 37 (1998) 4099-4102.
[21] B. Balamurugan and B. R. Mehta, “Optical and structural properties of nanocrystalline copper oxide thin films prepared by reactive evaporation”, Thin Solid Films, 396 (2001) 90-96.
[22] S. B. Ogale, P. G. Bilurkar, N. Mate, S. M. Kanetkar, N. Parikh and B. Patnaik, “Deposition of copper oxide thin films on different substrate by pulsed excimer laser ablation”, J. Appl. Phys., 72 (1992) 3765-3769.
[23] J. Lee and Y. Tak, “Electrochemical Deposition of a Single Phase of Pure Cu2O Films by Currents Modulation Methods”, Electrochem. and Solid-State Lett., 3 (2000) 69-72.
[24] T. Mahalingam, J. S. P. Chitra, J. P. Chu and P. J. Sebastian, “Preparation and microstructural studies of electrodeposition Cu2O thin films”, Materials Letters, 58 (2004) 1802-1807.
[25] T. Mahalingam, J. S. P. Chitra, J. P. Chu and P. J. Sebastian, “Structural and annealing studies of potentiostatically deposition Cu2O thin films”, Sol. Energy Mater. Sol. Cells, 88 (2005) 209-216.
[26] D. K. Zhang, Y. C. Liu, Y. L. Liu and H. Yang, “The electrical properties and the interfaces of Cu2O/ZnO/ITO p-i-n heterojunction”, Phys. B., 351 (2004) 178-183.
[27] S. Ishizuka, K. Suzuki, Y. Okamoto, M. Yanagita, T. Sakurai, K. Akimoto, N. Fujiwara, H. Kobayashi, K. Matsubara and S. Niki, “Polycrystalline n-ZnO/p-Cu2O heterojunctions grown by RF-magnetron sputtering”, Phys. Stat. Sol. (c), 1 (2004) 1067-1070.
[28] W. Y. Ching and Y. N. Xu, “Ground-state and optical properties of and CuO crystals”, Phys. Rev. B., 40 (1989) 7684-7695.
[29] 楊明輝, 透明導電膜, 藝軒圖書出版社, (2006). p. 18。
[30] 楊舜傑，“以反應性磁控濺鍍製備氧化亞銅薄膜以及其特性之分析、應用”，國立中山大學材料科學研究所，碩士論文，(2005)，p. 21〜22。
[31] H. Matsumura, A. Fujii and T. Kitatani, “Properties of High-Mobility Cu2O Films Prepared by Thermal Oxidation of Cu at Low Temperatures”, Jpn. J. Appl. Phys., 35 (1996) 5631-5636.
[32] J. H. Hsieh, P. W. Kuo, K. C. Peng, S. J. Liu, J. D. Hsueh and S. C. Chang, “Opto-electronic properties of sputtered-deposited Cu2O films treated with rapid thermal annealing”, Thin Solid Films, 516 (2008) 5449-5453.
[33] S. Ishizuka, S. Kata, T. Maruyama and K. Akimoto, “Nitrogen Doping into Cu2O Thin Films Deposited by Reactive Radio-Frequency Magnetron Sputtering”, Jpn. J. Appl. Phys., 40 (2001) 2765-2768.
[34] S. Ishizuka, S. Kato, Y. Okamoto and K. Akimoto, “Control of hole carrier density of polycrystalline Cu2O thin films by Si doping”, Appl. Phys. Lett., 80 (2001) 950-952.
[35] A. M. Ruiz, M. G. Moreno and N. Takeuchi, “First principles calculations of the electronic properties of bulk Cu2O, clean and doped with Ag, Ni, and Zn”, Solid State Sci., 5 (2003) 291-295.
[36] N. Kikuchi and K. Tonooka, “Electrical and structural properties of Ni-doped Cu2O films prepared by pulsed laser deposition”, Thin Solid Films, 486 (2005) 33-37.
[37] N. Kikuchi, K. Tonooka and E. Kusano, “Mechanisms of carrier generation and transport in Ni-doped Cu2O”, Vacuum, 80 (2006) 756-760.
[38] S. Ishizuka, S. Kato, Y. Okamoto, K. Akimoto, “Hydrogen treatment for polycrystalline nitrogen-doped Cu2O thin film”, J. Crystal. Growth, 237-239 (2002) 616-620.
[39] Y. Okamoto, S. Ishizuka, S. Kato, T. Sakurai, N. Fujiwara, H. Kobayashi and K. Akimoto, “Passivation of defects in nitrogen-doped polycrystalline Cu2O thin films by crown-ether cyanide treatment”, Appl. Phys. Lett., 82 (2003) 1060-1062.
[40] S. Ishizuka, S. Kato, Y. Okamoto, T. Sakurai, K. Akimoto, N. Fujiwara and H. Kobayashi, “Passivation of defects in polycrystalline Cu2O thin films by hydrogen or cyanide treatment”, Appl. Surf. Sci., 216 (2003) 94-97.
[41] Y. M. Lu, C. Y. Chen and M. H. Lin, “Effect of hydrogen plasma treatment on the electrical properties of sputtered N-doped cuprous oxide films”, Thin Solid Films, 480-481 (2005) 482-485.
[42] M. Fujinaka and A. A. Berezin, “Cuprous oxide-indium-tin oxide thin film photovoltaic cells”, J. Appl. Phys., 54 (1983) 3582-3588.
[43] J. Katayama, K. Ito, M. Matsuoka and J. Tamaki, “Performance of Cu2O/ZnO solar cell prepared by two-step electrodeposition”, J. Appl. Electrochem., 34 (2004) 687-692.
[44] T. Minami, H. Tanaka, T. Shimakawa, T. Miyata and H. Sato,“High-Efficiency Oxide Heterojunction Solar Cells Using Cu2O Sheets”, Jpn. J. Appl. Phys., 43 (2004) L917-L919.
[45] H. Tanaka, T. Shimakawa, T. Miyata, H. Sato and T. Minami, “Electrical and optical properties of TCO-Cu2O heterojunction devices“, Thin Solid Films, 469-470 (2004) 80-85.
[46] H. Tanaka, T. Shimakawa, T. Miyata, H. Sato and T. Minami, “Effect of AZO film depositions on the photovoltaic properties of AZO-Cu2O heterojunctions”, Appl. Surf. Sci., 244 (2005) 568-572.
[47] T. Minami, T. Miyata, K. Ihara, Y. Minamino and S. Tsukada, “Effect of ZnO film deposition methods on the photovoltaic properties of ZnO-Cu2O heterojunction devices”, Thin Solid Films, 494 (2006) 47-52.
[48] A. Mittiga, E. Saiza, F. Sarto, M. Tucci and R. Vasanthi, “Heterojunction solar cell with 2% efficiency based on a Cu2O substrate”, Appl. Phys. Lett., 88 (2006) 163502-1-163502-2.
[49] K. Akimoto, S. Ishizuka, M. Yanagita, Y. N. Goutam, K. Paul and T. Sakuria,“Thin film deposition of Cu2O and application for solar cells”, Sol. Energy, 80 (2006) 715-722.
[50] T. J. Hsueh, C. L. Hsu, S. J. Chang, P. W. Guo, J. H. Hsieh and I. C. Chen, “Cu2O/n-ZnO nanowire solar cells on ZnO:Ga/glass templates”, Scripta. Mater., 57 (2007) 53-56.
[51] 蕭宏, 半導體製程技術導論, 台灣培生教育出版股份有限公司, (2001)，p. 224〜464。
[52] 張勁燕, 半導體製程設備, 第二版, 五南圖書出版股份有限公司, (2004)，p. 359〜394。
[53] 白木靖寬, 吉田貞史, 薄膜工程學, 全華科技圖書股份有限公司, (2006)，p. 1-33〜1-39。
[54] J. A. Thornton, “Influence of apparatus geometry and deposition conditions on the structure and topography of thick sputtered coatings”, J. Vac. Sci. Technol., 11 (1974) 666-670.
[55] H. T. G. Hentzell, C. R. M. Grovenor and D. A. Smith,“Grain structure variation with temperature for evaporated mental films”, J. Vac. Sci. Technol. A., 2 (1984) 218-219.
[56] P. B. Barna and M. Adamik, “Fundamental structure forming phenomena of polycrystalline films and the structure zone models”, Thin Solid Films, 317 (1998) 27-33.
[57] 汪建民, “材料分析”, 中國材料科學學會, (1998)，p. 41〜267。
[58] J. Q. Miller, R. P. Chiarello, H. K. Kim, T. Roberts, H. You, R. T. Kampwirth and K. E. Gray, “Phase relationships in Cu-O thin films prepared by sputtering”, Appl. Phys. Lett., 59 (1991) 3174-3176.
[59] A. Parretta, M. K. Jayaaraj, A. D. Nocera, S. Loreti, L. Quercia and A. Agati, “Electrical and Optical Properties of Copper Oxide Films Prepared by Reactive RF Magnetron Sputtering”, Phys. Stat. Sol. (a), 155 (1996) 399-404.
[60] A. S. Reddy, H.H. Park, V. S. Reddy, K. V. S. Reddy, N. S. Sarma, S. Kaleemulla, S, Uthanna and P. S. Reddy, “Effect of sputtering power on the physical properties
of dc magnetron sputtered copper oxide thin films”, Mater Chem Phys., 110 (2008) 397-401.
[61] H. L. Chen, Y. M. Lu and W. S. Hwang, “Thickness dependence of electrical and optical properties of sputtered nickel oxide films”, Thin Solid Films, 514 (2006) 361-365.
[62] L. Ai, G. Fang, L. Yuan, N. Liu, M. Wang, C. Li, Q. Zhang, J. Li and X. Zhao, “Influence of substrate temperature on electrical and optical properties of p-type semitransparent conductive nickel oxide thin films deposited by radio frequency sputtering”, Appli. Surf. Sci., 254 (2008) 2401-2405.
[63] C. Jayewardena, K. P. Hewaparakrama, D. L. A Wijewardena and H. Guruge, “Fabrication of n-Cu2O electrodes with higher energy conversion efficiency in a photoelectrochemical cell”, Sol. Eenergy. Mater. Sol. Cells, 56 (1998) 29-33.
[64] C. A. N. Fernando and S. K. Wetthasinghe, “Investigation of photoelectrochemical characteristics of n-type Cu2O films”, Sol. Energy. Mater. Sol. Cells, 63 (2000) 299-308.
[65] C. A. N. Fernando, T. M. W. J. Bandara and S. K. Wethasingha, “H2 evolution from a photoelectrochemical cell with n-Cu2O photoelectrode under visible light irradiation”, Sol. Energy. Mater. Sol. Cells, 70 (2001) 121-129.
[66] G. L. Pearson and W. H. Brattain, “History of Semiconductor Research”, Proceeding of the IRE., (1955) 1794-1806.
[67] S. H. Mohamed, O. Kappertz, T. Niemeier, R. Drese, M. M. Wakkad and M. Wuttig, “Effect of heat treatment on structural , optical and mechanical properties of sputtered TiOxNy films”, Thin Solid Films, 468 (2004) 48-56.