Optical and Morphological Studies of Chemical Bath Deposited Nanocrystalline Cd_1-xZn_xS Thin Films

Kasim Uthman Isah

Department of Physics, Federal University of Technology, Minna, Nigeria.

DOI: 10.4236/msa.2013.45036                

Abstract

Cadmium Zinc Sulfide, Cd_1-xZn_xS thin films were deposited by chemical bath deposition technique at bath temperature of 75°C. The morphology of the films was analyzed by scanning electron microscope, the optical constants of the films were estimated from the transmission and reflection spectra of the films in the wavelength range of 300 - 900 nm. The films had a transmittance between 75% and 85% and optical band gap in the range 2.8 - 3.4 eV. The dependence of the refractive index of the films on the wavelength was investigated using the single oscillator model, from which the dispersion parameters were determined. The high frequency dielectric constant ε_L and the ratio of the carrier concentration to the effective mass N/m^* were estimated based on the Spitzer and Fan model. Both ε_L and N/m^* show a decrease in value with increase in Zinc content.

Keywords

Chemical Bath Deposition; Cd_1-xZn_xS; Scanning Electron Microscope

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	N. I. Kovtyukhova, E. V. Buzaneva, C .C. Waraksa and T. E. Mallouk, “Ultrathin Nanoparticle ZnS and ZnS: Mn films: Surface Sol-Gel Synthesis, Morphology, Photophysical Properties,” Materials Science and Engineering B, Vol. 69-70, 2000, pp. 411-417. HUdoi:10.1016/S0921-5107(99)00312-8U
[2]	J. Aguilar-Hernandez, J. Sastre-Hernandez, N. XimelloQuiebras, R. Mendoza-Perez, O. Vigil-Galan, G. ContrerasPuente and M. Cardenas-Garcia, “Photoluminescence Studies on CdS-CBD Films Grown by Using Different S/Cd ratios,” Thin Solid Films, Vol. 511-512, 2006, pp. 143-146. HUdoi:10.1016/j.tsf.2005.11.082U
[3]	D. Zubia, C. Lopez, M. Rodriguez, A. Escobedo, S. Oyer, L. Romo, S. Rogers, S. Quinonez and J. McClure, “Ordered CdTe/CdS Arrays for High-Performance Solar Cells,” Journal of Electrochemical Materials, Vol. 36, No. 12, 2007, pp. 1599-1603. HUdoi:10.1007/s11664-007-0276-4U
[4]	T. Chandra and S. Bhushan, “Photoconducting and Photovoltaic Studies on Some Chemically Deposited (Cd-Zn)S & (Cd-Pb)S Films,” Journal of Materials Science, Vol. 39, No. 20, 2004, pp. 6303-6309. HUdoi:10.1023/B:JMSC.0000043600.30625.d1U
[5]	T. D. Dzhafarov, F. Ongul and I. Karabay, “Formation of CdZnS Thin Films by Zn Diffusion,” Journal of Physics D, Appl Phys, Vol. 39, No. 15, 2006, pp. 3221. HUdoi:10.1088/0022-3727/39/15/001U
[6]	W. Wang, I. Germanenko and M. Samy El-Shall, “RoomTemperature Synthesis and Characterization of Nanocrystalline CdS, ZnS, and CdxZn1-xS,” Chemistry of Materials, Vol. 14, No. 7, 2002, pp. 3028-3033. HUdoi:10.1021/cm020040xU
[7]	T. Prem Kumar and K. Sankaranarayanan, “Growth and Characterization of CdZnS Thin Films by Short Duration Micro Wave Assisted-Chemical Bath Deposition Technique,” Chalcogenide Letters, Vol. 6, No. 10, 2009, pp. 555-562.
[8]	S. Ilican, M. Caglar and Y. Caglar, “The Effect of Deposition Parameters on the Physical Properties of CdxZn1-xS Films Deposited by Spray Pyrolysis Method,” Journal of Optoelectronics and Advanced Materials, Vol. 9, No. 5, 2007, pp. 1414-1417.
[9]	J. Lee, W. Songa, J. Yia, K. Yang, W. Han and J. Hwang, “Growth and Properties of the CdxZn1-xS Thin Films for Solar Cell Applications,” Thin Solid Films, Vol. 431-432, 2003, pp. 349-353. HUdoi:10.1016/S0040-6090(03)00526-1U
[10]	P. B. Smith, “Low Temperature, Low Pressure CdZnS Films Produced by Metalorganic Chemical Vapor Deposition,” Journal of Vacuum Science and Technology, Vol. 10, No. 4, 1992, pp. 897-902. HUdoi:10.1116/1.577691U
[11]	P. K. Ghosh, U. N. Maiti, S. F. Ahmed and K. K. Chattopadhyay, “Highly Conducting Transparent Nanocrystalline CdxZn1-xS Thin Film Synthesized by RF Magnetron Sputtering and Studies on Its Optical, Electrical and Field Emission Properties,” Solar Energy Materials & Solar Cells, Vol. 90, No. 16, 2006, pp. 2616-2629. HUdoi:10.1016/j.solmat.2006.02.015U
[12]	D. S. Boyle, O. Robbe, D. P. Halliday, M. R. Heinrich, A. Bayer, P. O’Brien, D. J. Otway and M. D. G. Potter, “A Novel Method for the Synthesis of the Ternary Thin Film Semiconductor Cadmium Zinc Sulfide from Acidic Chemical Baths,” Journal of Materials Chemistry, Vol. 10, 2000, pp. 2439-2441. HUdoi:10.1039/b005544lU
[13]	A. Abu EL-Fadl, G. A. Mohamad, A. B. Abd El-Moiz and M. Rashad, “Optical Constants of Zn1-xLixO Films Prepared by Chemical Bath Deposition Technique,” Physica B, Vol. 366, No. 1-4, 2005, pp. 44-54. HUdoi:10.1016/j.physb.2005.05.019U
[14]	G. F. Bassani and G. P. Parravicini, “Electronic States and Optical Transitions in Solids,” Pergamon Press, Oxford, 1989.
[15]	M. DiDomenico and S. H. Wemple, “Oxygen-Octahedra Ferroelectrics, I. Theory of Electro-Optical Effects,” Journal of Applied Physics, Vol. 40, No. 2, 1969, pp. 720-735. HUdoi:10.1063/1.1657458U
[16]	H. S. Afak, M. Merdan and O. F. Yüksel, “Dispersion Analysis of SnS and SnSe,” Turkish Journal of Physics, Vol. 26, No. 5, 2002, pp. 341347.
[17]	S. H. Wemple, “Refractive-Index Behaviour of Amorphous Semiconductors and Glasses,” Physics Review B, Vol. 7, No. 8, 1973, pp. 3767-3777. HUdoi:10.1103/PhysRevB.7.3767U
[18]	A. M. Salem, “Structure, Refractive-Index Dispersion and the Optical Absorption Edge of Chemically Deposited ZnxCd1-xS Thin Films,” Applied Physics A, Vol. 74, No. 2, 2002, pp. 205-211. HUdoi:10.1007/s003390100877U
[19]	S. Ilican, Y. Caglar and M. Caglar, “Effect of the Substrate Temperatures on the Optical Properties of the Cd0.22Zn0.78S Thin Films by Spray Pyrolysis Method,” Physica Macedonica, Vol. 56, 2006, pp. 43-48.
[20]	S. H. Wemple and M. Di Domenico Jr., “Optical DisperSion and Structure of Solids,” Physics Review Letters, Vol. 23, No. 20, 1969, pp. 1156-1160. HUdoi:10.1103/PhysRevLett.23.1156U
[21]	O. A. Azim, M. M. Abdel-Aziz and I. S. Yahia, “Structure and Optical Analysis of Ta2O5 Deposited on Infrasil Substrate,” Applied Surface Science, Vol. 255, No. 9, 2009, pp. 4829-4835. HUdoi:10.1016/j.apsusc.2008.11.084U
[22]	W. G. Spitzer and H. Y. Fan, “Determination of Optical Constants and Carrier Effective Mass of Semiconductors,” Physical Review, Vol. 106, No. 5, 1957, pp. 882890. HUdoi:10.1103/PhysRev.106.882U
[23]	M. M. El-Nahass, A. A. M. Farag, E. M. Ibrahim and S. Abd-El-Rahman, “Structural, Optical and Electrical Properties of Thermally Evaporated Ag2S Thin Films,” Vacuum, Vol. 72, No. 4, 2004, pp. 453-460. HUdoi:10.1016/j.vacuum.2003.10.005U