Effect of the Sulfur Concentration on the Optical Band Gap Energy and Urbach Tail of Spray-Deposited ZnS Films

Authors

1 Mechanical Engineering, Yazd University

2 Nanotechnology and Advanced Materials Department, , Materials and Energy Research Center (MERC)

3 Semiconductors, Materials and Energy Research Center (MERC)

Abstract

Zinc sulfide (ZnS) films were deposited through a simple and low cost spray pyrolytic technique using mixed aqueous solutions of zinc nitrate and thiourea. The structural and optical properties of these films were investigated as a function of initial (Zn:S) molar ratio in the precursor solution, which varied between (1:1) and (1:3). X-ray diffraction (XRD) analysis revealed that wurtzite zinc oxide (ZnO) and cubic ZnS phases formed in the film prepared by the equal molar ratio of zinc to sulfur ions and with increasing sulfur content in the precursor solution, only single cubic ZnS phase was appeared. The transmittance spectra measured by UV-Vis spectrophotometer indicated that with the increment of the sulfur content, the transmittance of the films increased in the visible and near infrared regions about 50% and the absorption edges shifted to shorter wavelengths. As a result, the band gap energy (Eg) increased from 3.43 to 3.72 eV and the band tail width (Eu) decreased from 553 to 259 meV, which is due to the phase composition and the decrement of structural defects. By extracting a linear relevance between the band gap energy and width of the band tail of ZnS, the optical band gap at Eu= 0 was estimated to be 3.977 eV.

Keywords

Main Subjects


1. Goudarzi, A., Motedayen Aval, G., Park, S.S., Choi, M.C., Sahraei, R., Ullah, M.H., Avane, A. and Ha, C.S., "Lowtemperature growth of nanocrystalline Mn-doped ZnS thin films prepared by chemical bath deposition and optical properties", Chemistry of Materials, Vol.21, (2009), 2375-2385.

2. Elidrissi, B., Addou, M., Regragui, M., Bougrine, A., Kachouane, A. and Bernède, J.C., "Structure, composition and optical properties of ZnS thin films prepared by spray pyrolysis", Materials Chemistry and Physics, Vol. 68, (2001), 175-179.

3. Saeed, N.M., "Structural and optical properties of ZnS thin films prepared by spray pyrolysis technique", Journal of Al-Nahrain University, Vol. 14, (2011), 86-92.

4. Yamaga, S., Yoshikawa, A. and Kasai, H., "Electrical and optical properties of donor doped ZnS films grown by lowpressure MOCVD", Journal of Crystal Growth, Vol. 86, (1988), 252-256.

5. Fang, X., Bando, Y., Meiyong Liao, M., Zhai, T., Gautam, U.K., Li, L., Koide, Y. and Golberg, D., "An efficient way to assemble ZnS nanobelts as ultraviolet-light sensors with enhanced photocurrent and stability", Advanced Functional Materials, Vol. 20, (2010), 500-508.

6. Salem, J.K., Hammad, T.M., Kuhn, S., Draaz, M.A., Hejazy, N.K. and Hempelmann, R., "Structural and optical properties of Co-doped ZnS nanoparticles synthesized by a capping agent", Journal of Materials Science: Materials in Electronics, Vol. 25, (2014), 2177-2182.

7. Wang, X., Huang, H., Liang, B., Liu, Z., Chen, D. and Shen, G., et al., "ZnS nanostructures: synthesis, properties, and applications", Critical Reviews in Solid State and Materials Sciences, Vol. 38, (2013), 57-90.

8. Zhai, T., Li, L., Ma, Y., Liao, M., Wang, X., Fang, X., Yao, J., Bando, Y. and Golberg, D., "One-dimensional inorganic nanostructures: synthesis, field-emission and photodetection", Chemical Society Reviews, Vol. 40, (2011), 2986-3004.

9. Dong, L., Liu, Y., Zhuo, Y. and Chu, Y., "General route to the fabrication of ZnS and M-Doped (M = Cd2+, Mn2+, Co2+, Ni2+ and Eu3+) ZnS nanoclews and a study of their properties", European Journal of Inorganic Chemistry, Vol. 2010, (2010), 2504-2513.

10. Bär, M., Ennaoui, A., Klaer, J., Kropp, T., Sáez-Araoz, R., Allsop, N., Lauermann, I., Scho, H.W. and Lux-Steiner, M.C., "Formation of a ZnS∕ Zn(S,O) bilayer buffer on CuInS2 thin film solar cell absorbers by chemical bath deposition", Journal of Applied Physics, Vol. 99, (2006), 064911.

11. Sohn, S. and Hamakawa, Y., "Excitation and deexcitation of acdriven thin-film ZnS electroluminescent devices", Journal of Applied Physics, Vol. 72, (1992), 2492-2504.

12. Bang, J.H., Helmich, R.J. and Suslick, K.S., "Nanostructured ZnS:Ni2+ photocatalysts prepared by ultrasonic spray pyrolysis", Advanced Materials, Vol. 20, (2008), 2599-2603.

13. Zeng, X., Pramana, S.S., Batabyal, S.K., Mhaisalkar, S.G., hena, X. and Jinesh, K.B., "Low temperature synthesis of wurtzite zinc sulfide (ZnS) thin films by chemical spray pyrolysis", Physical Chemistry Chemical Physics, Vol. 15, (2013), 6763-6768.

14. Zhang, L., Qin, D., Yang, G. and Zhang, Q., "The investigation on synthesis and optical properties of ZnS: Co nanocrystals by using hydrothermal method", Chalcogenide Letters, Vol. 9, (2012) 93-98.

15. Cao, J., Yang, J., Zhang, Y., Wang, Y., Yang, L., Wang, D., Liu, Y., Liu, X. and Xie, Z., "XAFS analysis and luminescent properties of ZnS:Mn2+ nanoparticles and nanorods with cubic and hexagonal structure", Optical Materials, Vol. 32, (2010), 643-647.

16. Sartale, S., Sankapal, B., Lux-Steiner, M.C. and Ennaoui, A., "Preparation of nanocrystalline ZnS by a new chemical bath deposition route", Thin Solid Films, Vol. 480, (2005), 168-172.

17. Durrani, S., Al-Shukri, A.M., Iob, A. and Khawaja, E.E., "Optical constants of zinc sulfide films determined from transmittance measurements", Thin Solid Films, Vol. 379, (2000), 199-202.

18. Shao, L. X., Chang, K. H.and Hwang, H. L., "Zinc sulfide thin films deposited by RF reactive sputtering for photovoltaic applications", Applied Surface Science, Vol. 212, (2003) 305- 310.

19. Tanskanen, J.T., Bakke, J.R., Bent, S. and Pakkanen, T., "ALD growth characteristics of ZnS films deposited from organozinc and hydrogen sulfide precursors", Langmuir, Vol. 26, (2010), 11899-11906.

20. Yokoyama, M., Kashiro, K.I. and Ohta, S.I., "High quality zinc sulfide epitaxial layers grown on (100) silicon by molecular beam epitaxy", Applied Physics Letters, Vol. 49, (1986), 411- 412.

21. Yano, S., Schroeder, R., Ullrich, B. and Sakai, H., "Absorption and photocurrent properties of thin ZnS films formed by pulsedlaser deposition on quartz", Thin Solid Films, Vol.423, (2003), 273-276.

22. Dean, P., Pitt, A.D., Skolnick, M.S., Wright, P.J. and Cockayne, B., "Optical properties of undoped organometallic grown ZnSe and ZnS", Journal of Crystal Growth, Vol. 59, (1982), 301- 306.

23. Chamberlin, R. and Skarman, J., "Chemical spray deposition process for inorganic films", Journal of the Electrochemical Society, Vol. 113, (1966), 86-89.

24. Shinde, S.D., Patil, G.E., Kajale, D.D., Gaikwad, V.B. and Jain, G.H., "Synthesis of ZnO nanorods by spray pyrolysis for H2S gas sensor", Journal of Alloys and Compounds, Vol. 528, (2012), 109-114.

25. Addou, M., Moumin, A., B, E., Regragui, M., Bougrine, A., Kachouane, A. and Monty, C., "Structural, optical and electrical properties of undoped and indium doped zinc oxide prepared by spray pyrolysis", Journal de Chimie Physique et de Physico- Chimie Biologique, Vol. 96, (1999), 232-244.

26. Boo, J. H., Lee, S.B., Yu, K.S., Koh, W. and Kim, Y., "Growth of magnesium oxide thin films using single molecular precursors by metal–organic chemical vapor deposition", Thin Solid Films, Vol. 341, (1999), 63-67.

27. Sharma, R., Lakshmikumar, S.T., Singh, G. and Rastogi, A.C., "Photoluminescence in manganese indium sulphide thin films deposited by chemical spray pyrolysis", Materials Chemistry and Physics, Vol. 92, (2005), 240-244.

28. Ben Nasrallah, T., Amlouk, M., Bernède, J.C. and Belgacem, S., "Structure and morphology of sprayed ZnS thin films", Physica Status Solidi (A), Vol. 201, (2004), 3070-3076.

29. Dedova, T., Krunks, M., Volobujeva, O. and Oja, I., "ZnS thin films deposited by spray pyrolysis technique", Physica Status Solidi (C), Vol. 2, (2005), 1161-1166.

30. Lopez, M.C, Espinos, J.P., Martín, F., Leinen, D. and Ramos- Barrado, J.R., "Growth of ZnS thin films obtained by chemical spray pyrolysis: The influence of precursors", Journal of Crystal Growth, Vol. 285, (2005), 66-75.

31. Hernandez-Fenollosa, M.A, López, M.C., Donderis, V., González, M., Marí., B. and Ramos-Barrado, J.R., "Role of precursors on morphology and optical properties of ZnS thin films prepared by chemical spray pyrolysis", Thin Solid Films, Vol. 516, (2008), 1622-1625.

32. Poornima, N., Jose, A., Kartha, C.S. and Vijayakumar, K.P., "Composition and conductivity-type analysis of spray pyrolysed ZnS thin films using photoluminescence", Energy Procedia, Vol. 15, (2012), 347-353.

33. Afifi, H., Mahmoud, S. and Ashour, A., "Structural study of ZnS thin films prepared by spray pyrolysis", Thin Solid Films, Vol. 263, (1995), 248-251.

34. Su, B. and Choy, K., "Electrostatic assisted aerosol jet deposition of CdS, CdSe and ZnS thin films", Thin Solid Films,Vol. 361, (2000), 102-106.

35. Tohge, N., Tamaki, S. and Okuyama, K., "Formation of fine particles of zinc sulfide from thiourea complexes by spray pyrolysis", Japanese Journal of Applied Physics, Vol. 34, (1995), L207.

36. Sharma, H.K., Shukla, P. and Agrawal, S., "Effect of Sulphur concentration on the structural and electronic properties of ZnS nanoparticles synthesized using chemical precipitation method", Journal of Materials Science: Materials in Electronics, Vol. 28, (2017), 6226-6232.

37. Dedova, T., Krunks, M., Gromyko, I., Mikli, V., Sildos, I., Utt, K. and Unt, T., "Effect of Zn:S molar ratio in solution on the properties of ZnS thin films and the formation of ZnS nanorods by spray pyrolysis", Physica Status Solidi (A), Vol. 211, (2014), 514-521.

38. Lindroos, S., Kanniainen, T. and Leskelä, M., "Growth of zinc sulfide thin films by the successive ionic layer adsorption and reaction (SILAR) method on polyester substrates", Materials Research Bulletin, Vol. 32, (1997), 1631-1636.

39. Johnston, D., Carletto, M.H., Reddy, K.R.T., Forbes, I. and Miles, R.W., "Chemical bath deposition of zinc sulfide based buffer layers using low toxicity materials", Thin Solid Films, Vol. 403, (2002), 102-106.

40. Barreca, D., A. Gasparotto, A., Tondello, E., Sada, C., Polizzi, S. and Benedetti, A., "Nucleation and growth of nanophasic CeO2 thin films by Plasma-Enhanced CVD", Chemical Vapor Deposition, Vol. 9, (2003), 199-206.

41. Ayouchi, R., Martin, F., Leinen, D., Ramos-Barrado, J.R., "Growth of pure ZnO thin films prepared by chemical spray pyrolysis on silicon", Journal of Crystal Growth, Vol. 247, (2003), 497-504.

42. Urbach, F., "The long-wavelength edge of photographic sensitivity and of the electronic absorption of solids", Physical Review, Vol. 92, (1953), 1324.

43. Ikhmayies, S.J. and Ahmad-Bitar, R.N., "A study of the optical bandgap energy and Urbach tail of spray-deposited CdS: In thin films", Journal of Materials Research and Technology, Vol. 2, (2013), 221-227.

44. Rothwarf, A., Meakin, J. and Bamett, A., "Polycrystalline and amorphous thin films and devices", 1980, Academic Press, New York.

45. Yakuphanoglu, F., Ilican, S., Caglar, M. and Çağlar, Y.Y., "The determination of the optical band and optical constants of noncrystalline

and crystalline ZnO thin films deposited by spray pyrolysis", Journal of Optoelectronics and Advanced Materials, Vol. 9, (2007), 2180-2185.

46. Aly, K., et al., "Optical properties of Ge–As–Te thin films", Physica B: Condensed Matter, Vol. 406, (2011), 4227-4232.

47. Melsheimer, J. and Ziegler, D., Band gap energy and Urbach tail studies of amorphous, partially crystalline and polycrystalline tin dioxide, Thin Solid Films, Vol. 129, (1985), 35-47.