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.