Abstract
The formation of a copper-deficient surface layer is a common phenomenon in CuInSe₂ thin films, typically arising in deposition processes that involve multiple steps, such as thermal treatment and post-selenization. Here, we studied the radio-frequency magnetron sputtering film deposition from a CuInSe₂ target. Substrate temperature varied between 50 and 400°C. X-ray photoelectron spectroscopy (XPS) confirmed the persistent presence of a Cu-deficient surface layer across all deposition temperatures. Films grown below 200°C were amorphous and Cu-deficient, while at 200°C and above, the films exhibited a transition to a polycrystalline chalcopyrite structure, as evidenced by X-ray diffraction (XRD). The crystallite size for the polycrystalline films deposited at 200°C and 400°C was approximately 10–12 nm. Energy dispersive spectroscopy (EDS) revealed a progressive decrease in copper content from ~20 at.% at 50–200°C to ~16 at.% at 400°C, while indium remained nearly constant and selenium increased slightly from 50 at.% to 56 at.% with increasing temperature. UV-Vis spectroscopy showed that the optical bandgap (Eg) decreased from 1.2 eV at 50°C and 1.15 eV at 100°C to approximately 0.95–0.94 eV at 200°C and 400°C. Our results provide valuable insights into the effect of substrate temperature on CuInSe2 thin films, contributing to the ongoing efforts to optimize their properties for photovoltaic and optoelectronic applications.
References
Chandran, R., & Mallik, A. (2018). Electrodeposition of near stoichiometric CuInSe₂ thin films for photovoltaic applications. IOP Conference Series: Materials Science and Engineering, 338, 012018. https://doi.org/10.1088/1757-899X/338/1/012018
Chauhan, S. M., Chaki, S. H., Deshpande, M. P., Malek, T. J., & Tailor, J. P. (2018). Thermal decomposition study on CuInSe₂ single crystals. International Journal of Thermophysics, 39, 18. https://doi.org/10.1007/s10765-017-2341-4
Cheng, K. W., Jhang, H. J., Li, C. T., & Ho, K. C. (2017). Solution-growth-synthesized Cu(In,Ga)Se₂ nanoparticles in ethanol bath for the applications of dye-sensitized solar cell and photoelectrochemical reaction. Journal of the Taiwan Institute of Chemical Engineers, 74, 136–145. https://doi.org/10.1016/j.jtice.2017.02.010
Cheng, Y. S., Wang, N. F., Tsai, Y. Z., Lin, J. J., & Houng, M. P. (2017). Investigation of CuInSe₂ nanowire arrays with core–shell structure electrodeposited at various duty cycles into anodic alumina templates. Applied Surface Science, 396, 631–636. https://doi.org/10.1016/j.apsusc.2016.10.207
Fan, P., Liang, G. X., Cai, X. M., Zheng, Z. H., & Zhang, D. P. (2011). The influence of annealing temperature on the structural, electrical and optical properties of ion beam sputtered CuInSe₂ thin films. Thin Solid Films, 519, 5348–5352. https://doi.org/10.1016/j.tsf.2011.02.036
Green, M. A., Dunlop, E. D., Yoshita, M., Kopidakis, N., Bothe, K., Siefer, G., Hao, X., & Jiang, J. Y. (2024). Solar cell efficiency tables (Version 60). Progress in Photovoltaics: Research and Applications, 33, 3–15. https://doi.org/10.1002/pip.3867
Hodes, G., & Cahen, D. (1986). Electrodeposition of CuInSe₂ and CuInS₂ films. Solar Cells, 16, 245–254. https://doi.org/10.1016/0379-6787(86)90088-8
Ishizuka, S., Nishinaga, J., Beppu, K., Maeda, T., Aoyagi, F., Wada, T., Yamada, A., Chantana, J., Nishimura, T., Minemoto, T., Monirul Islam, M., Sakurai, T., & Terada, Y. (2022). Physical and chemical aspects at the interface and in the bulk of CuInSe₂-based thin-film photovoltaics. Journal of Physical Chemistry Chemical Physics, 24, 1262. https://doi.org/10.1039/D1CP04495H
Jošt, M., Köhnen, E., Al-Ashouri, A., Bertram, T., Tomšič, Š., Magomedov, A., Kasparavicius, E., Kodalle, T., Lipovšek, B., Getautis, V., Schlatmann, R., Kaufmann, C. A., Albrecht, S., & Topič, M. (2022). Perovskite/CIGS tandem solar cells: From certified 24.2% toward 30% and beyond. ACS Energy Letters, 7, 1298–1307. https://doi.org/10.1021/acsenergylett.2c00274
Kim, S. T., Yoo, J. S., Lee, M. W., Jung, J. W., & Jang, J. H. (2022). CuInSe₂-based near-infrared photodetector. Applied Sciences, 12, 92. https://doi.org/10.3390/app12010092
Li, L., Chen, Y., Lv, Z., Yin, N. Q., Li, S., Wang, K., & Li, P. (2022). In situ one-step synthesis of CuInS₂ thin films with different morphologies and their optical properties. Journal of Materials Science: Materials in Electronics, 33, 2995–3001. https://doi.org/10.1007/s10854-021-07499-6
Li, L., Li, M., & Li, P. (2021). Cu(In,Ga)S₂ nanowire arrays: Self-templated synthesis and application for photoelectrochemical water splitting. Materials Characterization, 172, 110900. https://doi.org/10.1016/j.matchar.2021.110900
Mahraj, I., & Ptok, A. (2024). First-principles investigations of structural, electronic and optical properties of ternary chalcopyrite semiconductors CuInY₂ (Y = S, Se and Te). Computational Condensed Matter, 40, e00935. https://doi.org/10.1016/j.cocom.2024.e00935
Malitckaya, M., Komsa, H., Havu, V., & Puska, M. J. (2017). Effect of alkali metal atom doping on the CuInSe₂-based solar cell absorber. The Journal of Physical Chemistry C, 121(29), 15516–15528. https://doi.org/10.1021/acs.jpcc.7b03083
Maeda, T., Gong, W., & Wada, T. (2016). Crystallographic and optical properties and band structures of CuInSe₂, CuIn₃Se₅, and CuIn₅Se₈ phases in Cu-poor Cu₂Se–In₂Se₃ pseudo-binary system. Japanese Journal of Applied Physics, 55, 04ES15. https://doi.org/10.7567/JJAP.55.04ES15
Migliorato, P., Shay, J. L., & Kasper, H. M. (1975). Electrical properties and luminescence of CuInSe₂. Journal of Electronic Materials, 4, 209–222. https://doi.org/10.1007/BF02655402
Muzzillo, C. P., Li, J. V., Mansfield, L. M., Ramanathan, K., & Anderson, T. J. (2018). Surface and bulk effects of K in highly efficient Cu₁₋ₓKₓInSe₂ solar cells. Solar Energy Materials and Solar Cells, 185, 45–53. https://doi.org/10.1016/j.solmat.2018.05.013
Nanayakkara, S. U., Horowitz, K., Kanevce, A., Woodhouse, M., & Basore, P. (2017). Evaluating the economic viability of CdTe/CIS and CIGS/CIS tandem photovoltaic modules. Progress in Photovoltaics, 25, 271–279. https://doi.org/10.1002/pip.2849
Neumann, H. (1986). Optical properties and electronic band structure of CuInSe₂. Solar Cells, 16, 317–333. https://doi.org/10.1016/0379-6787(86)90092-X
Paulson, P. D., Birkmire, R. W., & Shafarman, W. N. (2003). Optical characterization of CuIn₁₋ₓGaₓSe₂ alloy thin films by spectroscopic ellipsometry. Journal of Applied Physics, 94, 879–888. https://doi.org/10.1063/1.1581345
Sadono, A., Hino, M., Nakada, K., & Yamada, A. (2018). Effect of an additional Cu-deficient layer deposition on alkali treated Cu(In,Ga)Se₂ solar cells deposited at low temperature. Solar Energy Materials and Solar Cells, 184, 67–72. https://doi.org/10.1016/j.solmat.2018.04.030
Sharma, S., Khan, K., Soni, M., Ahuja, U., Soni, A., & Sahariya, J. (2023). Investigation of electronic and optical properties of alkali atom doped CuInSe₂ using density functional theory. Physica Scripta, 98, 085927. https://doi.org/10.1088/1402-4896/ace489
Sobol, P. E., Nelson, A. J., Schwerdtfeger, C. R., Stickle, W. F., & Moulder, J. F. (2021). Single crystal CuInSe₂ analysis by high resolution XPS. Surface Science Spectra, 1, 393–397. https://doi.org/10.1116/1.1247638
Solhtalab, N., Mohammadi, M. H., Eskandari, M., & Fathi, D. (2022). Efficiency improvement of half-tandem CIGS/perovskite solar cell by designing nano-prism nanostructure as the controllable light trapping. Energy Reports, 8, 1298–1308. https://doi.org/10.1016/j.egyr.2021.12.038
Stanbery, B. J., Abou-Ras, D., Yamada, A., & Mansfield, L. (2021). CIGS photovoltaics: Reviewing an evolving paradigm. Journal of Physics D: Applied Physics, 55, 173001. https://doi.org/10.1088/1361-6463/ac4363
Thomere, A., Barreau, N., Stephant, N., Guillot-Deudon, C., Gautron, E., Caldes, M. T., & Lafond, A. (2022). Formation of Cu(In,Ga)S₂ chalcopyrite thin films following a 3-stage co-evaporation process. Solar Energy Materials and Solar Cells, 237, 111563. https://doi.org/10.1016/j.solmat.2021.111563
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Copyright (c) 2025 Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales