Structural and optical study of titanium dioxide thin films elaborated by APCVD for application in silicon solar cells

Abstract

In this work, titanium dioxide (TiO2) thin films have been deposited on glass and monocrystalline silicon by Atmospheric Pressure Chemical Vapor Deposition (APCVD) technique using titanium tetrachloride TiCl4 as precursor. The structural, electrical and optical properties of the prepared TiO2 thin films were evaluated by Atomic Force Microscopy (AFM), Four Point Probe (FPP) and Spectroscopic Ellipsometry (SE), respectively. These properties were exploited for application of the TiO2 layers as antireflection coatings on monocrystalline silicon solar cells. Our experimental results show that the deposited TiO2 thin films were polycrystalline, homogenous, compact and relatively smooth. The measured average optical transmittance of the TiO2 films was about 85-90%. From the ellipsometry analysis, the refractive index of our TiO2 thin films was found to be n=2,25 at the wavelength λ= 550 nm, with a thickness of 56,2 nm. These experimental results obtained by APCVD are in excellent agreement with the computed results of the TiO2 refractive index and thickness required for a high quality antireflection coating in industrial conditions. The obtained results demonstrate the real opportunity of the APCVD technique to prepare high quality antireflection coatings for crystalline solar cells. This indicates that the APCVD antireflection coatings may have a high potential industrial application.