Characterization of the Energy Band Diagram of Fabricated SnO2/CdS/CdTe Thin Film Solar Cells

Authors: Rasha A. Abdullah, Mohammed. A. Razooqi, Adwan N. H. Al-Ajili

Abstract:

A SnO2/CdS/CdTe heterojunction was fabricated by thermal evaporation technique. The fabricated cells were annealed at 573K for periods of 60, 120 and 180 minutes. The structural properties of the solar cells have been studied by using X-ray diffraction. Capacitance- voltage measurements were studied for the as-prepared and annealed cells at a frequency of 102 Hz. The capacitance- voltage measurements indicated that these cells are abrupt. The capacitance decreases with increasing annealing time. The zero bias depletion region width and the carrier concentration increased with increasing annealing time. The carrier transport mechanism for the CdS/CdTe heterojunction in dark is tunneling recombination. The ideality factor is 1.56 and the reverse bias saturation current is 9.6×10-10A. The energy band lineup for the n- CdS/p-CdTe heterojunction was investigated using current - voltage and capacitance - voltage characteristics.

Keywords: SnO2/CdS/CdTe heterojunction, XRD, C-V measurement, I-V measurement, energy band diagram.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1087013

References:

[1] Lin H., Irfan, Xia W., Wu H.N., Gao Y., Tang C.W. MgOx back contact for CdS/CdT thin film solar cells: Preparation, device characteristics and stability. Solar Energy Materials & Solar Cells 2012; 99:349-355.
[2] Kranz L., Perrenoud J., Pianezzi F., Gretener C., Rossbach P., Buecheler S., Tiwari A.N. Effect of Sodiumon recrystallization and photovoltaic properties of CdTe solar cells. Solar Energy Materials & Solar Cells 2012; 105:213-219.
[3] Bai Z. and WangD. Oxidation of CdTe thin film in air coated with and without a CdC12 layer. Phys. Status Solidi A 2012;209: 1982-1987.
[4] Li B., Liu J., Xu G., Lu R., Feng L., and Wu J. Development of pulsed laser deposition for CdS/CdTe thin film solar cells. Applied Physics Letters 2012; 101:153903-1-153903-4.
[5] Mohammed W.F., Daoud 0. and Al-Tikriti M. Power conversion enhancement of CdS/CdTe solar cell interconnected with tunnel diode. Circuits and Systems 2012; 3:230-237.
[6] Castillo-Alvarado F.L., Inoue-Chavez A.J., Vigil-Galan 0., Sanchez¬Mez E., Lopez-Chavez E. and Contreras-Puente G. C-V calculations in CdS/CdTe thin films solar cells. Thin Solid Films 2010; 518:1796-1798.
[7] Chun S., Lee S., Jun Y., Ba J.S., Kim J., Kim D. Wet chemical etched CdTe thin film solar cells. Current Applied Physics 2013; 13:211-216.
[8] Zhu Y., Li Z., Chen M., Cooper H.M., Lu G.Q. and Xu Z.P. One-pot preparation of highly fluorescent cadmium telluride/cadmium sulfide quantum dots under neutral-pH condition for biological applications. Journal of Colloid and Interface Science 2013; 390:3-10.
[9] Al Dhafiri A.M. Isothermal and isochronal studies of structural and electrical properties of CdTe. Crys. Res. Techno. 2001; 37:950-957.
[10] Enriquez J.P. and Mathew X. XRD study of the grain growth in CdTe films annealed at different temperatures. Solar Energy & Solar Cells 2004; 81:363-369.
[11] Nakamura K., Gotoh M., Fujihara T., Toyama T. and Okamoto H. Influence of CdS window layer on 2-um thick CdS/CdTe thin film solar cells. Solar Energy & Solar Cells 2003; 75:185-192.
[12] Lee J.H., Lim D. and Yi J. Electrical and optical properties of CdTe films prepared by vacuum evaporation with close spacing source and substrate. Solar Energy Materials & Solar Cells 2003; 75:235-242.
[13] Razykov T.M., Contreras-Puente G., Chomokur G.C., Dybjec M., Emirov Y., Ergashev B., Ferekides C.S., Hubbimov A., Ikramov B., Kouchkarov K.M., Mathew X., Morel D., Ostapenko S., Sanchez-Meza E., Stefanakos E., Upadhyaya H.M., Vigil-Galan 0. and Vorobiev Y.V.Structural, photoluminescent and electrical properties of CdTe films with different compositions fabricated by CMBD. Solar Energy 2009; 83: 90-93.
[14] Lyahovitskaya V., Chemyak L., Greenberg J., Kaplan L., and Cahen D. Low temperature, postgrowth self-doping of CdTe single crystals due to controlled deviation from stoichiometry. Journal of Applied Physics 2000;88: 3976.
[15] Milnes A.G. and Feucht D.L. Hetrojunctions and metal-semiconductor junctions. London: Academic press; 1972.
[16] Yun J.H., Kim K.H., Lee D.Y. and Aim B.T. Contact formation using Cu2Te as Cu doping source and electrode in CdTe. Solar Energy Materials & Solar Cells 2003; 75:201-210.
[17] Alnajjar A.A., Alias M.F.A., Almatuk R.A. and Al-Douri A.A. The characteristic of anisotype CdS/CdTe heterojunction. J. Renewable Energy 2009; 34:2160-2163.
[18] Green M.A. Solar cells; operating principles, technology and system applications. New Jersey: Prince-Hall Inc; 1982.
[19] Sharma B.L. and Purohit R.K. Semiconductor heterojunction. New York: Pergamon Press; 1974.
[20] Huijin S., Xiaoli W., Jiagui Z., Qiang Y. Study of CuTe polycrystalline thin films for CdTe solar cells. 2010 Asia-Pacific Power and Energy Engineering Conference, IEEE; 2010.
[21] Shaaban E.R., Afify N. and El-Taher A. Effect of film thickness on microstructural parameters and optical constants of CdTe thin films. Journal of Alloys and Compounds 2009; 482:400-404.
[22] Senthamilselvi V., Ravichandran K. and Saravanakumar K. Influence of immersion cycles on the stoichiometry of CdS films deposited by SILAR technique. Journal of Physics and Chemistry of Solids 2013; 74:65-69.
[23] Fritsche J., Kraft D., Thissen A., Mayer Th., Klien A. and Jaegermann W. Interface engineering of chalcogenide semiconductors in thin film solar cells: CdTe as an example. Mat. Res. Soc. Symp. Prcc. 2001; 668:H6.6.1-H6.6.12.
[24] Sze S.M. Physics of semiconductor devices. 5th ed, New York: John Wiley and Sons; 2007.