Optimization Of Thickness Of Sb2Te3 Thin Film As Back Contact For CdTe Thin Film Solar Cells

Department of Electronic Science, Bangalore University, Jnanabharathi, Bangalore 560056, Karnataka, Indi

Adv. Mater. Lett., 2014, 5 (11), pp 639-644

DOI: 10.5185/amlett.2014.7589

Publication Date (Web): Nov 09, 2014

Copyright © IAAM-VBRI Press

E-mail: hm_mahesh@rediffmail.com

Abstract

Sb₂Te₃ thin films of different thickness ranging from 100 to 500 nm were prepared on glass substrate by thermal evaporation method. The effects of thickness on structural, optical and electrical properties of thin films were studied. XRD revealed that grain size increases from 1.1 to 98.7 nm with increase in film thickness. The internal strain and dislocation density decreased with increase in film thickness. The optical band gap decreases from 1.3 to 0.9 eV with increase in film thickness. AFM images indicated crystalline nature of Sb₂Te₃. Surface roughness increased up to 400nm after which it decreased. The resistivity decreases with increase in thickness at room temperature ranging from 2.9×10^-3 to 1.35×10^-4 ohm.cm. The work function and barrier height decreases as the film thickness increases from 5.45 to 5.05eV and barrier height from 0.3 to -0.1eV. The results elucidate that Sb₂Te₃back contact of 400 nm thickness is ideal and efficient to be used in CdTe solar cell.

Keywords

Antimony telluride, Sb₂Te_3,thermal evaporation, optical band gap, work function, electrical characteristrics