Influence of Wrinkle Structure on Properties of Na-doped ZnO Films
Main Article Content
Abstract
Un-doped ZnO and Na-doped ZnO (NZO) thin films with various Na doping concentrations were successfully fabricated on glass substrates by a sol-gel process. The effect of Na ions at concentrations of 0, 1, 2, 3, 4, and 5% on the crystalline structure, surface morphology, and optoelectronic properties of ZnO films was studied using appropriate measurement techniques. XRD analysis revealed a polycrystalline hexagonal wurtzite structure in the NZO films. The NZO films' average crystal size ranged from 17.7 nm to 19.6 nm. SEM micrographs showed that wrinkle network appeared in the pure and doped ZnO films due to solvent evaporation during the thermal annealing process. UV-Vis spectroscopy pointed out that the average transmittance of NZO films is as large as ca. 78%. The optical bandgap of the films varied slightly between 3.235 eV for the pure ZnO and 3.246 eV for the Na 5% doped NZO film. When Na ions were doped into the NZO films, the electrical conductivity improved. Moreover, the absorption figure of merit exhibited the largest value of 0.981 Ω-1cm-1 for the fabricated NZO films, which enables the use of these films for solar cells and for other optoelectronic applications.
Keywords:
Na-doped ZnO, wrinkle network, absorption figure of merit.
References
[1] Ü. Özgür, Y. I. Alivov, C. Liu, A. Teke, M. A. Reshchikov, S. Doğan, V. Avrutin, S. J. Cho, H. Morkoç,
A Comprehensive Review of ZnO Materials and Devices, J. Appl. Phys., Vol. 98, 2005, pp. 041301.
[2] Q. Li, K. Cheng, W. Weng, P. Du, G. Han, Synthesis, Characterization and Electrochemical Behaviour of Sb-Doped ZnO Microsphere Film, Thin Solid Films, Vol. 544, 2013, pp. 466-471.
[3] M. D. McCluskey, S. J. Jokela, Defects in ZnO, J. Appl. Phys., Vol. 106, 2009, pp. 071101.
[4] J. C. Fan, K. M. Sreekanth, Z. Xie, S. L. Chang, K. V. Rao, P-type ZnO Materials: Theory, Growth, Properties and Devices, Prog. Mater. Sci., Vol. 58, 2013, pp. 874-985.
[5] Z. N. Ng, K. Y. Chan, S. Muslimin, D. Knipp, P-type Characteristic of Nitrogen-doped ZnO Films, J. Electron. Mater., Vol. 47, 2018, pp. 5607-5613.
[6] K. K. Kim, H. S. Kim, D. K. Hwang, J. H. Lim, S. J. Park, Realization of p-type ZnO Thin Films Via Phosphorus Doping and Thermal Activation of the Dopant, Appl. Phys. Lett., Vol. 83, 2003, pp. 63-65.
[7] P. Biswas, P. Nath, D. Sanyal, P. Banerji, An Alternative Approach to Investigate the Origin of P-type Conductivity in Arsenic Doped ZnO, Current Applied Physics, Vol. 15, 2015, pp. 1256-1261.
[8] S. V. Mohite, K. Y. Rajpure, Synthesis and Characterization of Sb Doped ZnO Thin Films for Photodetector Application, Opt. Mater., Vol. 36, 2014, pp. 833-838.
[9] L. M. Mahajan, C. K. Kasar, D. S. Patil, Investigation of Optical and Electrical Properties of Lithium Doped ZnO Nano Films, Mater. Res. Express, Vol. 6, 2019, pp. 045053.
[10] S. Lin, J. Lu, Z. Ye, H. He, X. Gu, L. Chen, J. Huang, B. J. S. S. C. Zhao, P-type Behaviour in Na-doped ZnO Films and ZnO Homojunction Light-Emitting Diodes, Vol. 148, 2008, pp. 25-28.
[11] S. Guan, L. Wang, Y. Tamamoto, M. Kato, Y. Lu, X. Zhao, Fabrication and Characterization of Potassium-Doped ZnO Thin Films, J. Mater. Sci.: Mater. Electron., Vol. 32, 2021, pp. 669-675.
[12] E. C. Lee, K. J. Chang, Possible P-type Doping with Group-I Elements in ZnO, Phys. Rev. B, Vol. 70, 2004,
pp. 115210.
[13] C. H. Park, S. B. Zhang, S. H. Wei, Origin of P-type Doping Difficulty in ZnO: The Impurity Perspective, Phys. Rev. B, Vol. 66, 2002, pp. 073202.
[14] S. S. Lin, J. G. Lu, Z. Z. Ye, H. P. He, X. Q. Gu, L. X. Chen, J. Y. Huang, B. H. Zhao, P-type Behavior in Na-Doped ZnO Films and ZnO Homojunction Light-emitting Diodes, Solid State Commun, Vol. 148, 2008,
pp. 25-28.
[15] P. Ding, X. H. Pan, Z. Z. Ye, J. Y. Huang, H. H. Zhang, W. Chen, C. Y. Zhu, Realization of P-type Non-polar A-Plane ZnO Films Via Doping of Na Acceptor, Solid State Commun., Vol. 156, 2013, pp. 8-11.
[16] L. W. Wang, F. Wu, D. X. Tian, W.J. Li, L. Fang, C. Y. Kong, M. Zhou, Effects of Na Content on Structural and Optical Properties of Na-doped ZnO Thin Films Prepared by Sol–gel Method, J. Alloys Compd., Vol. 623, 2015, pp. 367-373.
[17] J. G. Cuadra, S. Porcar, D. Fraga, T. S. Lyubenova, J. B. Carda, Enhanced Electrical Properties of Alkali-doped Zno Thin Films with Chemical Process, Solar, Vol. 1, 2021, pp. 30-40.
[18] S. K. Kim, S. A. Kim, C. H. Lee, H. J. Lee, S. Y. Jeong, C. R. Cho, The Structural and Optical Behaviors of K-Doped ZnO∕Al2O3 (0001) Films, Appl. Phys. Lett., Vol. 85, 2004, pp. 419-421.
[19] L. Xu, X. Li, J. Yuan, Effect of K-doping on Structural and Optical Properties of ZnO Thin Films, Superlattices Microstruct., Vol. 44, 2008, pp. 276-281.
[20] H. B. Liu, X. H. Pan, J. Y. Huang, H. P. He, Z. Z. Ye, Preparation of Na Delta-doped P-type ZnO Thin Films by Pulsed Laser Deposition Using NaF and ZnO Ceramic Targets, Thin Solid Films, Vol. 540, 2013, pp. 53-57.
[21] H. Shen, X. Zhao, L. Duan, R. Liu, H. Li, B. Wang, Effect of NaZn/Nai Ratio on Structural, Optical, and Electrical Properties of Na-doped ZnO Thin Films, J. Appl. Phys., Vol. 121, 2017, pp. 155303.
[22] R. Maity, S. Das, M. K. Mitra, K. K. Chattopadhyay, Synthesis and Characterization of ZnO Nano/Microfibers Thin Films by Catalyst Free Solution Route, Phys. E, Vol. 25, 2005, pp. 605-612.
[23] S. Kumar, R. Thangavel, Structural and Optical Properties of Na Doped ZnO Nanocrystalline Thin Films Synthesized Using Sol–gel Spin Coating Technique, J. Sol-Gel Sci. Technol., Vol. 67, 2013, pp. 50-55.
[24] J. Lü, K. Huang, J. Zhu, X. Chen, X. Song, Z. Sun, Preparation and Characterization of Na-doped ZnO Thin Films by Sol–gel Method, Phys. B, Vol. 405, 2010, pp. 3167-3171.
[25] S. Ilican, Y. Caglar, M. Caglar, F. Yakuphanoglu, Electrical Conductivity, Optical and Structural Properties of Indium-doped ZnO Nanofiber Thin Film Deposited by Spray Pyrolysis Method, Phys. E, Vol. 35, 2006, pp. 131-138.
[26] X. S. Wang, Z. C. Wu, J. F. Webb, Z. G. Liu, Ferroelectric and Dielectric Properties of Li-doped ZnO Thin Films Prepared by Pulsed Laser Deposition, Appl. Phys. A, Vol. 77, 2003, pp. 561-565.
[27] K. Navin, R. Kurchania, Structural, Morphological and Optical Studies of Ripple-Structured ZnO Thin Films, Appl. Phys. A, Vol. 121, 2015, pp. 1155-1161.
[28] H. T. Kim, S. Y. Lee, C. Park, Controls of Surface Morphology on Sol-Gel Derived ZnO Films Under Isothermal Treatment Conditions, Vacuum, Vol. 143, 2017, pp. 312-315.
[29] S. J. Kwon, J. H. Park, J. G. Park, Wrinkling of a Sol-gel-derived Thin Film, Phys. Rev. E, Vol. 71, 2005,
pp. 011604.
[30] M. S. Kim, K. G. Yim, D. Y. Lee, J. S. Kim, J. S. Kim, J. S. Son, J. Y. Leem, Effects of Cooling Rate and Post-Heat Treatment on Properties of ZnO Thin Films Deposited by Sol–gel Method, Appl. Surf. Sci., Vol. 257, 2011, pp. 9019-9023.
[31] D. C. Lim, W. H. Shim, K. D. Kim, H. O. Seo, J. H. Lim, Y. Jeong, Y. D. Kim, K. H. Lee, Spontaneous Formation of Nanoripples on the Surface of ZnO Thin Films As Hole-Blocking Layer of Inverted Organic Solar Cells, Sol. Energy Mater. Sol. Cells, Vol. 95, 2011, pp. 3036-3040.
[32] G. W. Scherer, Sintering of Sol-gel Films, J. Sol-Gel Sci. Technol., Vol. 8, 1997, pp. 353-363.
[33] N. Sekine, C. H. Chou, W. L. Kwan, Y. Yang, ZnO Nano-Ridge Structure and Its Application in Inverted Polymer Solar Cell, Org. Electron., Vol. 10, 2009, pp. 1473-1477.
[34] J. W. Choi, J. W. Jin, D. Tondelier, Y. Bonnassieux, B. Geffroy, Low Temperature Solution-processable 3D-Patterned Charge Recombination Layer for Organic Tandem Solar Cells, Materials, Vol. 12, 2019, pp. 162.
[35] X. L. Zhang, K. S. Hui, K. N. Hui, High Photo-responsivity ZnO UV Detectors Fabricated by RF Reactive Sputtering, Mater. Res. Bull., Vol. 48, 2013, pp. 305-309.
[36] B. N. Q. Trinh, T. D. Chien, N. Q. Hoa, D. H. Minh, Solution-processable Zinc Oxide Based Thin Films with Different Aluminum Doping Concentrations, J. Sci.: Adv. Mater. Devices, Vol. 5, 2020, pp. 497-501.
[37] A. Chelouche, T. Touam, F. Boudjouan, D. Djouadi, R. Mahiou, A. Bouloufa, G. Chadeyron, Z. Hadjoub, Na Doping Effects on the Structural, Conduction Type and Optical Properties of Sol–gel ZnO Thin Films, J. Mater. Sci.: Mater. Electron., Vol. 28, 2017, pp. 1546-1554.
[38] S. H. Wu, S. Kumar, R. Thangavel, S. U. Jen, W. C. Cheng, Y. C. Chang, Erratum to: Structural and Optical Properties of Na Doped ZnO Nanocrystalline Thin Films Synthesized Using Sol–gel Spin Coating Technique,
J. Sol-Gel Sci. Technol., Vol. 71, 2014, pp. 192.
[39] S. S. Lin, Z. Z. Ye, J. G. Lu, H. P. He, L. X. Chen, X. Q. Gu, J. Y. Huang, L. P. Zhu, B. H. Zhao, Na Doping Concentration Tuned Conductivity of ZnO Films Via Pulsed Laser Deposition and Electroluminescence from ZnO homojunction on Silicon Substrate, J. Phys. D: Appl. Phys., Vol. 41, 2008, pp. 155114.
[40] Z. Zheng, Y. F. Lu, Z. Z. Ye, H. P. He, B. H. Zhao, Carrier Type- and Concentration-Dependent Absorption and Photoluminescence of ZnO Films Doped with Different Na Contents, Mater. Sci. Semicond. Process, Vol. 16, 2013, pp. 647-651.
[41] H. Q. Nguyen, D. V.Nguyen, A. Fujiwara, B. N. Q. Trinh, Solution-processed CuO Thin Films with Various Cu2+ Ion Concentrations, Thin Solid Films, Vol. 660, 2018, pp. 819-823.
[42] J. J. Loferski, Thin Films and Solar Energy Applications, Surf. Sci., Vol. 86, 1979, pp. 424-443.
[43] F. Alharbi, J. D. Bass, A. Salhi, A. Alyamani, H. C. Kim, R. D. Miller, Abundant Non-Toxic Materials for Thin Film Solar Cells: Alternative to Conventional Materials, Renewable Energy, Vol. 36, 2011, pp. 2753-2758.
A Comprehensive Review of ZnO Materials and Devices, J. Appl. Phys., Vol. 98, 2005, pp. 041301.
[2] Q. Li, K. Cheng, W. Weng, P. Du, G. Han, Synthesis, Characterization and Electrochemical Behaviour of Sb-Doped ZnO Microsphere Film, Thin Solid Films, Vol. 544, 2013, pp. 466-471.
[3] M. D. McCluskey, S. J. Jokela, Defects in ZnO, J. Appl. Phys., Vol. 106, 2009, pp. 071101.
[4] J. C. Fan, K. M. Sreekanth, Z. Xie, S. L. Chang, K. V. Rao, P-type ZnO Materials: Theory, Growth, Properties and Devices, Prog. Mater. Sci., Vol. 58, 2013, pp. 874-985.
[5] Z. N. Ng, K. Y. Chan, S. Muslimin, D. Knipp, P-type Characteristic of Nitrogen-doped ZnO Films, J. Electron. Mater., Vol. 47, 2018, pp. 5607-5613.
[6] K. K. Kim, H. S. Kim, D. K. Hwang, J. H. Lim, S. J. Park, Realization of p-type ZnO Thin Films Via Phosphorus Doping and Thermal Activation of the Dopant, Appl. Phys. Lett., Vol. 83, 2003, pp. 63-65.
[7] P. Biswas, P. Nath, D. Sanyal, P. Banerji, An Alternative Approach to Investigate the Origin of P-type Conductivity in Arsenic Doped ZnO, Current Applied Physics, Vol. 15, 2015, pp. 1256-1261.
[8] S. V. Mohite, K. Y. Rajpure, Synthesis and Characterization of Sb Doped ZnO Thin Films for Photodetector Application, Opt. Mater., Vol. 36, 2014, pp. 833-838.
[9] L. M. Mahajan, C. K. Kasar, D. S. Patil, Investigation of Optical and Electrical Properties of Lithium Doped ZnO Nano Films, Mater. Res. Express, Vol. 6, 2019, pp. 045053.
[10] S. Lin, J. Lu, Z. Ye, H. He, X. Gu, L. Chen, J. Huang, B. J. S. S. C. Zhao, P-type Behaviour in Na-doped ZnO Films and ZnO Homojunction Light-Emitting Diodes, Vol. 148, 2008, pp. 25-28.
[11] S. Guan, L. Wang, Y. Tamamoto, M. Kato, Y. Lu, X. Zhao, Fabrication and Characterization of Potassium-Doped ZnO Thin Films, J. Mater. Sci.: Mater. Electron., Vol. 32, 2021, pp. 669-675.
[12] E. C. Lee, K. J. Chang, Possible P-type Doping with Group-I Elements in ZnO, Phys. Rev. B, Vol. 70, 2004,
pp. 115210.
[13] C. H. Park, S. B. Zhang, S. H. Wei, Origin of P-type Doping Difficulty in ZnO: The Impurity Perspective, Phys. Rev. B, Vol. 66, 2002, pp. 073202.
[14] S. S. Lin, J. G. Lu, Z. Z. Ye, H. P. He, X. Q. Gu, L. X. Chen, J. Y. Huang, B. H. Zhao, P-type Behavior in Na-Doped ZnO Films and ZnO Homojunction Light-emitting Diodes, Solid State Commun, Vol. 148, 2008,
pp. 25-28.
[15] P. Ding, X. H. Pan, Z. Z. Ye, J. Y. Huang, H. H. Zhang, W. Chen, C. Y. Zhu, Realization of P-type Non-polar A-Plane ZnO Films Via Doping of Na Acceptor, Solid State Commun., Vol. 156, 2013, pp. 8-11.
[16] L. W. Wang, F. Wu, D. X. Tian, W.J. Li, L. Fang, C. Y. Kong, M. Zhou, Effects of Na Content on Structural and Optical Properties of Na-doped ZnO Thin Films Prepared by Sol–gel Method, J. Alloys Compd., Vol. 623, 2015, pp. 367-373.
[17] J. G. Cuadra, S. Porcar, D. Fraga, T. S. Lyubenova, J. B. Carda, Enhanced Electrical Properties of Alkali-doped Zno Thin Films with Chemical Process, Solar, Vol. 1, 2021, pp. 30-40.
[18] S. K. Kim, S. A. Kim, C. H. Lee, H. J. Lee, S. Y. Jeong, C. R. Cho, The Structural and Optical Behaviors of K-Doped ZnO∕Al2O3 (0001) Films, Appl. Phys. Lett., Vol. 85, 2004, pp. 419-421.
[19] L. Xu, X. Li, J. Yuan, Effect of K-doping on Structural and Optical Properties of ZnO Thin Films, Superlattices Microstruct., Vol. 44, 2008, pp. 276-281.
[20] H. B. Liu, X. H. Pan, J. Y. Huang, H. P. He, Z. Z. Ye, Preparation of Na Delta-doped P-type ZnO Thin Films by Pulsed Laser Deposition Using NaF and ZnO Ceramic Targets, Thin Solid Films, Vol. 540, 2013, pp. 53-57.
[21] H. Shen, X. Zhao, L. Duan, R. Liu, H. Li, B. Wang, Effect of NaZn/Nai Ratio on Structural, Optical, and Electrical Properties of Na-doped ZnO Thin Films, J. Appl. Phys., Vol. 121, 2017, pp. 155303.
[22] R. Maity, S. Das, M. K. Mitra, K. K. Chattopadhyay, Synthesis and Characterization of ZnO Nano/Microfibers Thin Films by Catalyst Free Solution Route, Phys. E, Vol. 25, 2005, pp. 605-612.
[23] S. Kumar, R. Thangavel, Structural and Optical Properties of Na Doped ZnO Nanocrystalline Thin Films Synthesized Using Sol–gel Spin Coating Technique, J. Sol-Gel Sci. Technol., Vol. 67, 2013, pp. 50-55.
[24] J. Lü, K. Huang, J. Zhu, X. Chen, X. Song, Z. Sun, Preparation and Characterization of Na-doped ZnO Thin Films by Sol–gel Method, Phys. B, Vol. 405, 2010, pp. 3167-3171.
[25] S. Ilican, Y. Caglar, M. Caglar, F. Yakuphanoglu, Electrical Conductivity, Optical and Structural Properties of Indium-doped ZnO Nanofiber Thin Film Deposited by Spray Pyrolysis Method, Phys. E, Vol. 35, 2006, pp. 131-138.
[26] X. S. Wang, Z. C. Wu, J. F. Webb, Z. G. Liu, Ferroelectric and Dielectric Properties of Li-doped ZnO Thin Films Prepared by Pulsed Laser Deposition, Appl. Phys. A, Vol. 77, 2003, pp. 561-565.
[27] K. Navin, R. Kurchania, Structural, Morphological and Optical Studies of Ripple-Structured ZnO Thin Films, Appl. Phys. A, Vol. 121, 2015, pp. 1155-1161.
[28] H. T. Kim, S. Y. Lee, C. Park, Controls of Surface Morphology on Sol-Gel Derived ZnO Films Under Isothermal Treatment Conditions, Vacuum, Vol. 143, 2017, pp. 312-315.
[29] S. J. Kwon, J. H. Park, J. G. Park, Wrinkling of a Sol-gel-derived Thin Film, Phys. Rev. E, Vol. 71, 2005,
pp. 011604.
[30] M. S. Kim, K. G. Yim, D. Y. Lee, J. S. Kim, J. S. Kim, J. S. Son, J. Y. Leem, Effects of Cooling Rate and Post-Heat Treatment on Properties of ZnO Thin Films Deposited by Sol–gel Method, Appl. Surf. Sci., Vol. 257, 2011, pp. 9019-9023.
[31] D. C. Lim, W. H. Shim, K. D. Kim, H. O. Seo, J. H. Lim, Y. Jeong, Y. D. Kim, K. H. Lee, Spontaneous Formation of Nanoripples on the Surface of ZnO Thin Films As Hole-Blocking Layer of Inverted Organic Solar Cells, Sol. Energy Mater. Sol. Cells, Vol. 95, 2011, pp. 3036-3040.
[32] G. W. Scherer, Sintering of Sol-gel Films, J. Sol-Gel Sci. Technol., Vol. 8, 1997, pp. 353-363.
[33] N. Sekine, C. H. Chou, W. L. Kwan, Y. Yang, ZnO Nano-Ridge Structure and Its Application in Inverted Polymer Solar Cell, Org. Electron., Vol. 10, 2009, pp. 1473-1477.
[34] J. W. Choi, J. W. Jin, D. Tondelier, Y. Bonnassieux, B. Geffroy, Low Temperature Solution-processable 3D-Patterned Charge Recombination Layer for Organic Tandem Solar Cells, Materials, Vol. 12, 2019, pp. 162.
[35] X. L. Zhang, K. S. Hui, K. N. Hui, High Photo-responsivity ZnO UV Detectors Fabricated by RF Reactive Sputtering, Mater. Res. Bull., Vol. 48, 2013, pp. 305-309.
[36] B. N. Q. Trinh, T. D. Chien, N. Q. Hoa, D. H. Minh, Solution-processable Zinc Oxide Based Thin Films with Different Aluminum Doping Concentrations, J. Sci.: Adv. Mater. Devices, Vol. 5, 2020, pp. 497-501.
[37] A. Chelouche, T. Touam, F. Boudjouan, D. Djouadi, R. Mahiou, A. Bouloufa, G. Chadeyron, Z. Hadjoub, Na Doping Effects on the Structural, Conduction Type and Optical Properties of Sol–gel ZnO Thin Films, J. Mater. Sci.: Mater. Electron., Vol. 28, 2017, pp. 1546-1554.
[38] S. H. Wu, S. Kumar, R. Thangavel, S. U. Jen, W. C. Cheng, Y. C. Chang, Erratum to: Structural and Optical Properties of Na Doped ZnO Nanocrystalline Thin Films Synthesized Using Sol–gel Spin Coating Technique,
J. Sol-Gel Sci. Technol., Vol. 71, 2014, pp. 192.
[39] S. S. Lin, Z. Z. Ye, J. G. Lu, H. P. He, L. X. Chen, X. Q. Gu, J. Y. Huang, L. P. Zhu, B. H. Zhao, Na Doping Concentration Tuned Conductivity of ZnO Films Via Pulsed Laser Deposition and Electroluminescence from ZnO homojunction on Silicon Substrate, J. Phys. D: Appl. Phys., Vol. 41, 2008, pp. 155114.
[40] Z. Zheng, Y. F. Lu, Z. Z. Ye, H. P. He, B. H. Zhao, Carrier Type- and Concentration-Dependent Absorption and Photoluminescence of ZnO Films Doped with Different Na Contents, Mater. Sci. Semicond. Process, Vol. 16, 2013, pp. 647-651.
[41] H. Q. Nguyen, D. V.Nguyen, A. Fujiwara, B. N. Q. Trinh, Solution-processed CuO Thin Films with Various Cu2+ Ion Concentrations, Thin Solid Films, Vol. 660, 2018, pp. 819-823.
[42] J. J. Loferski, Thin Films and Solar Energy Applications, Surf. Sci., Vol. 86, 1979, pp. 424-443.
[43] F. Alharbi, J. D. Bass, A. Salhi, A. Alyamani, H. C. Kim, R. D. Miller, Abundant Non-Toxic Materials for Thin Film Solar Cells: Alternative to Conventional Materials, Renewable Energy, Vol. 36, 2011, pp. 2753-2758.