Zn₂SnO₄ Thin Films for Photovoltaics: Structural Optimization and Charge Transport Analysis
Abstract
In this study, (Zn,Sn)O thin films were synthesized and characterized for potential application as buffer layers in photovoltaic devices. The films were deposited using thermal evaporation in a high-vacuum chamber, followed by a controlled oxidation process in a pure oxygen atmosphere to achieve a ZnO-based oxide layer. Post-deposition annealing was conducted at various temperatures (400°C‑550°C) to enhance crystallinity and phase composition. X-ray diffraction (XRD) analysis confirmed the formation of a highly crystalline Zn2SnO4 phase, with the optimal structure obtained at 550°C. Optical characterization revealed a temperature-dependent bandgap narrowing effect, significantly influencing transmittance and reflectance spectra. Electrical properties were assessed via Hall effect and current-voltage (I-V) measurements, indicating an increase in carrier mobility and conductivity at higher annealing temperatures. The charge transport mechanism in Ni-(Zn,Sn)O-pSi-Ni heterostructures was analyzed using the space-charge-limited current (SCLC) model, revealing that carrier injection is the dominant transport process. The results demonstrate that (Zn,Sn)O thin films exhibit superior optoelectronic properties, making them promising candidates for photovoltaic and optoelectronic applications.
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M.K. Pham, P.H. Dang, and T.V. Huynh, “Studying the structural, optical, and electrical characteristics of Zn2SnO4 films using a direct current magnetron sputtering method,” Ceramics International, 50(4), 6824-6835 (2023). https://doi.org/10.1016/j.ceramint.2023.12.026
N.M. Martin, T. Törndahl, M. Babucci, F. Larsson, K.A. Simonov, D. Gajdek, L.R. Merte, et al., “Atomic Layer Grown Zinc Tin Oxide as an Alternative Buffer Layer for Cu2ZnSnS4-Based Thin Film Solar Cells: Influence of Absorber Surface Treatment on Buffer Layer Growth,” ACS Applied Energy Materials, 5(11), 13971–13980 (2022). https://doi.org/10.1021/acsaem.2c02579
E. Gnenna, N. Khemiri, and M. Kanzari, “Development and characterization of (Zn,Sn)O thin films for photovoltaic application as buffer layers,” SN Appl. Sci. 2(2), 1–9 (2020). https://doi.org/10.1007/S42452-020-1971-5
Z.X. Mirzajonov, K.A. Sulaymonov, T.I. Rakhmonov, F.T. Yusupov, D.Sh. Khidirov, and J.S. Rakhimjonov, “Advancements in Zinc Oxide (ZnO) thin films for photonic and optoelectronic applications: a focus on doping and annealing processes,” E3S Web of Conferences, 549, 03013 (2024). https://doi.org/10.1051/e3sconf/202454903013
N.A. Sultanov, Z.X. Mirzajonov, F.T. Yusupov, and T.I. Rakhmonov, “Nanocrystalline ZnO Films on Various Substrates: A Study on Their Structural, Optical, and Electrical Characteristics,” East European Journal of Physics, (2), 309-314 (2024). https://doi.org/10.26565/2312-4334-2024-2-35
F.T. Yusupov, T.I. Rakhmonov, M.F. Akhmadjonov, M.M. Madrahimov, and S.S. Abdullayev, “Enhancing ZnO/Si Heterojunction Solar Cells: A Combined Experimental and Simulation Approach,” East European Journal of Physics, (3), 425 434 (2024). https://doi.org/10.26565/2312-4334-2024-3-51
N.E. Sung, H.K. Lee, K.H. Chae, J.P. Singh, and I.J. Lee, “Correlation of oxygen vacancies to various properties of amorphous zinc tin oxide films,” J. Appl. Phys. 122, 085304 (2017). https://doi.org/10.1063/1.5000138
Shajan, Nirmal and Dhanasingh, Bharathi Mohan, “RF magnetron sputtering of Zn2SnO4 thin films: optimising microstructure, optical and electrical properties for photovoltaics,” Journal of Materials Science: Materials in Electronics, 35, 882 (2024). https://doi.org/10.1007/s10854-024-12648-8
V.V. Ganbavle, M.A. Patil, H.P. Deshmukh, and K.Y. Rajpure, “Development of Zn2SnO4 thin films deposited by spray pyrolysis method and their utility for NO2 gas sensors at moderate operating temperature,” J. Anal. Appl. Pyrolysis, 107, 233 241 (2014). https://doi.org/10.1016/j.jaap.2014.03.006
B. Zaidi, N. Houaidji, A. Khadraoui, S. Gagui, C. Shekhar, Y. Özen, K. Kamli, et al., “Structural, Optical and Electrical Properties of ZnxSn1-xS Thin Films Deposited by Chemical Spray Pyrolysis,” Journal of Nano Research, 61, 72–77 (2020). https://doi.org/10.4028/WWW.SCIENTIFIC.NET/JNANOR.61.72
X. Li, Z. Su, S. Venkataraj, S.K. Batabyal, and L.H. Wong, “8.6% Efficiency CZTSSe solar cell with atomic layer deposited Zn–Sn–O buffer layer,” Sol. Energy Mater. Sol. Cells, 157, 101–107 (2016). https://doi.org/10.1016/j.solmat.2016.05.032
M.K. Jayaraj, K.J. Saji, K. Nomura, T. Kamiya, and H. Hosono, “Optical and electrical properties of amorphous zinc tin oxide thin films examined for thin film transistor application,” J. Vac. Sci. Technol. B, 26, 495 (2008). https://doi.org/10.1116/1.2839860
R. Ramarajan, M. Kovendhan, D.T. Phan, K. Thangaraju, R.R. Babu, K.J. Jeon, and D.P. Joseph, “Optimization of Zn2SnO4 thin film by post oxidation of thermally evaporated alternate Sn and Zn metallic multi-layers,” Appl. Surf. Sci. 449, 68-76 (2018). https://doi.org/10.1016/j.apsusc.2018.01.029
M.S. Abd Aziz, M.S. Salleh, G. Krishnan, N. Mufti, M.F. Bin Omar, and S.W. Harun, “Structural, Morphological and Optical Properties of Zinc Oxide Nanorods prepared by ZnO seed layer Annealed at Different Oxidation Temperature,” Malaysian Journal of Fundamental and Applied Sciences, 18(3), 383–392 (2022). https://doi.org/10.11113/mjfas.v18n3.2538
S.W. Chang, K. Ishikawa, and M. Sugiyama, “RF magnetron sputtering deposition of amorphous Zn–Sn–O thin films as a buffer layer for CIS solar cells,” Phys Status Solidi C, 12, 688–691 (2015). https://doi.org/10.1002/pssc.201400255
J.Y. Hwang, and S.Y. Lee, “Effect of Annealing Temperature on Electrical Properties and Stability of Si–Zn–Sn–O Thin Film Transistors Under Temperature Stress,” Transactions on Electrical and Electronic Materials, 19(1), 15–19 (2018). https://doi.org/10.1007/S42341-018-0011-2
R. Acharya, Y.Q. Zhang, and X.A. Cao, “Characterization of zinc–tin–oxide films deposited by thermal co-evaporation,” Thin Solid Films, 520, 6130–6133 (2012). https://doi.org/10.1016/j.tsf.2012.05.087
K. Ellmer, “Hall Effect and Conductivity Measurements in Semiconductor Crystals and Thin Films,” in: Characterization of Materials, (2012), pp. 1–16. https://doi.org/10.1002/0471266965.COM035.PUB2
A. Treglia, F. Ambrosio, S. Martani, G. Folpini, A.J. Barker, M.D. Albaqami, F. De Angelis, et al., “Effect of electronic doping and traps on carrier dynamics in tin halide perovskites,” Materials Horizons, 9(6), 1763–1773 (2022). https://doi.org/10.1039/d2mh00008c
D. Rode, and J. Cetnar, “Electron mobility of heavily doped semiconductors including multiple scattering by ionized impurities,” Journal of Applied Physics, 134, 075701 (2023). https://doi.org/10.1063/5.0165201
N. Sultanov, Z. Mirzajonov, and F. Yusupov, “Technology of production and photoelectric characteristics of AlB 10 heterojunctions based on silicon,” E3S Web of Conferences, 458, 01013 (2023). https://doi.org/10.1051/e3sconf/202345801013
J.H. Lee, B.H. Lee, J. Kang, M.S. Diware, K. Jeon, C. Jeong, S.Y. Lee, and K.H. Kim, “Characteristics and Electronic Band Alignment of a Transparent p-CuI/n-SiZnSnO Heterojunction Diode with a High Rectification Ratio,” Nanomaterials, 11(5), 1237 (2021). https://doi.org/10.3390/NANO11051237
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