Influence of process parameters on band gap of Al-doped ZnO film

Abstract

This paper presents the influence of process parameters, such as argon (Ar) flow rate, sputtering power and substrate temperature on the band gap of Al-doped ZnO film, Al-doped ZnO thin films were fabricated by radio frequency (RF) magnetron sputtering technology and deposited on polyimide and glass substrates. Under different Ar flow rates varied from 30 to 70 sccm, the band gap of thin films were changed from 3.56 to 3.67 eV. As sputtering power ranged from 125 to 200 W, the band gap was varied from 3.28 to 3.82 eV; the band gap was between 3.41 and 3.88 eV as substrate temperature increases from 150°C to 300°C. Furthermore, the correlation between carrier concentration and band gap was investigated by HALL. These results demonstrate that the band gap of the Al-doped ZnO thin film can be adjusted by changing the Ar flow rate, sputtering power and substrate temperature, which can improve the performance of semiconductor devices related to Al-doped ZnO thin film.

Keywords

Al-doped ZnO thin films / band gap / carrier concentration / argon (Ar) flow rate / sputtering power / substrate temperature

References

[1] Wang X J, Zeng X B, Huang D Q, Zhang X, Li Q. The properties of Al doped ZnO thin films deposited on various substrate materials by RF magnetron sputtering. Journal of Materials Science: Materials in Electronics, 2012, 23(8): 1580–1586

[2] Wang X J, Zeng X B,Huang D Q, Zhang X, Li Q. Structural, electrical and optical properties of aluminum doped zinc oxide deposited on glass and polyimide by RF magnetron sputtering method. Laser & Optoelectronics Progress, 2012, 49(4): 173–178

[3] Ma Q, Ye Z, He H, Zhu L, Zhao B. Effects of deposition pressure on the properties of transparent conductive ZnO: Ga films prepared by DC reactive magnetron sputtering. Materials Science in Semiconductor Processing, 2007, 10(4-5): 167–172

[4] Grundmann M, Wenckstern H, Pickenhain R, Nobis Th, Rahm A, Lorenz M. Electrical properties of ZnO thin films and optical properties of ZnO-based nanostructures. Superlattices and Microstructures, 2005, 38(4-6): 317–328

[5] Cao H T, Pei Z L, Gong J, Sun C, Huang R F, Wen L S. Transparent conductive Al and Mn doped ZnO thin films prepared by DC reactive magnetron sputtering. Surface and Coatings Technology, 2004, 184(1): 84–92

[6] Jin Z C, Hamberg I, Granqvist C G. Optical properties of sputter-deposited ZnO:Al thin films. Applied Physics (Berlin), 1988, 64(10): 5117–5131

[7] Henley S J, Ashfold M N R, Cherns D. The growth of transparent conducting ZnO films by pused laser ablation. Surface and coatings Technology, 2004, 177–178: 271–276

[8] Carlsson J M, Domingos H S, Bristowe P D, Hellsing B.An interfacial complex in ZnO and its influence on charge transport. Physical Review Letters, 2003, 91(16): 165506

[9] Oba F, Adachi H, Tanaka I. Energetics and electronic structure of point defects associated with oxygen excess at a tilt boundary of ZnO. Journal of Materials Research, 2000, 15(10): 2167–2175

[10] Yang Y Y, Zeng X B, Zeng Y, Liu L, Chen Q K. Deposition of quasi-crystal Al-doped ZnO thin films for photovoltaic device applications. Applied Surface Science, 2010, 257(1): 232–238

[11] Minami T. New n-type transparent conducting oxides. MRS Bulletin, 2000, 25(08): 38–44

[12] Xiu X W, Pang Z Y, Lv M S, Dai Y, Ye L, Han S. Transparent conducting molybdenum-doped zinc oxide films deposited by RF magnetron sputtering. Applied Surface Science, 2007, 253(6): 3345–3348

[13] Olvera M de la L, Maldonado A, Asomoza R, Solorza O, Acosta D R. Characteristics of ZnO:F thin films obtained by chemical spray. Effect of the molarity and the doping concentration. Thin Solid Films, 2001, 394(1- 2): 241–248

[14] Fang G, Li D, Yao B L. Fabrication and characterization of transparent conductive ZnO:Al thin films prepared by direct current magnetron sputtering with highly conductive ZnO(ZnAl₂O₄) ceramic target. Journal of Crystal Growth, 2003, 247(3-4): 393–400

[15] Yang W, Liu Z, Peng D L, Zhang F, Huang H, Xie Y, Wu Z. Room-temperature deposition of transparent conducting Al-doped ZnO films by RF magnetron sputtering method. Applied Surface Science, 2009, 255(11): 5669–5673

[16] Guo X L, Tabata H, Kawai T. Epitaxial growth and optoelectronic properties of nitrogen-doped ZnO films on Al₂O₃ substrate. Journal of Crystal Growth, 2002, 237-239: 544–547

[17] Hao X T, Ma J, Zhang D H, Yang Y G, Ma H L, Cheng C F, Liu X D. Comparison of the properties for ZnO:Al films deposited on polyimide and glass substrates. Materials Science and Engineering B, 2002, 90(1-2): 50–54

[18] Lee H J, Lee J A, Lee J H, Heo Y W, Kim J J, Park S K, Lim J. Optical band gap modulation by Mg-doping in In₂O₃(ZnO)₃ ceramics. Ceramics International, 2012, 38: 6693–6697

[19] Wu Y F, Chen H Y. Prediction of band gap reduction and magnetism in (Cu,S)-codoped ZnO. Journal of Magnetism and Magnetic Materials, 2012, 324(13): 2153–2157

[20] Liu Y, Hou Q Y, Xu H P, Zhao C W, Zhang Y. The band gap broadening and absorption spectrum of wurtzite Zn_1-xCo_xO from first-principles calculations. Chemical Physics Letters, 2012, 551: 72–77

[21] Lin C K, Zhao D, Gao W Y, Yang Z, Ye J, Xu T, Ge Q, Ma S, Liu D J. Tunability of band gaps in metal-organic frameworks. Inorganic Chemistry, 2012, 51(16): 9039–9044

[22] Duan L B, Zhao X R, Liu J M, Geng W C, Sun H N, Xie H Y. Band gap modified Al-doped Zn_1-xMg_xO and Zn_1-yCd_yO transparent conducting thin films. Journal of Materials Science: Materials in Electronics, 2012, 23(5): 1016–1021

[23] Aydın CAl-Hartomy O A, Al-Ghamdi A A, Al-Hazmi F, Yahia I S, El-Tantawy F, Yakuphanoglu F. Controlling of crystal size and optical band gap of CdO nanopowder semiconductors by low and high Fe contents. Journal of Electroceramics, 2012, 29(2): 155–162

[24] Ma S Z, Liang H K, Wang X H, Zhou J, Li L T, Sun C Q. Controlling the band gap of ZnO by programmable annealing. Journal of Physical Chemistry C, 2011, 115: 20487–20490

[25] Moon Y K, Bang B, Kim H, Jeong C O, Park J W. Effects of working pressure on the electrical and optical properties of aluminum-doped zinc oxide thin films. Journal of Materials Science Materials in Electronics, 2008, 19(6): 528–532

[26] Kappertz O, Drese R, Ngaruiya J M, Wuttig M. Reactive sputter deposition of zinc oxide: Employing resputtering effects to tailor film properties. Thin Solid Films, 2005, 484(1-2): 64–67

[27] Kamat P V, Dimitrijevic N M, Nozik A J. Dynamic burstein-moss shift in semiconductor colloids. Journal of Physical Chemistry, 1989, 93(8): 2873–2875

[28] Nobbs J H. Kubelka-Munk theory and the predication of reflectance. Review of Progress in Coloration and Related Topics, 1985, 15(1): 66–75

[29] Liu Y P, Chen F, Guo A B, Li B, Dan M, Liu M H, Hu X W. Preparation and application of transparent conductive AZO thin film. Vacuum and Cryogenics, 2007, 13(1): 1–6

Acknowledgements

This work was funded by supporting technology project of Ministry of Education of China (No. 62501040202). The authors would like to thank all members in the Photonics And Information System Integration Institute for their supports. And then, we also thank teachers in Micro-nano manufacturing center in Wuhan National Laboratory for Optoelectronics. At last special acknowledges for the XRD, HALL and SEM analyses from Analytical and Testing Center of Huazhong University of Science and Technology.

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2014 Higher Education Press and Springer-Verlag Berlin Heidelberg