2
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ꢀ
ꢁ
ꢀ
ꢁ
1
ꢀλ
λ
q =
ε
molar
(8)
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500
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[
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where ꢀλ is the absorption half bandwidth. In order to evaluate
the oscillator strengths and the electric dipole strength, a Gaus-
sian fit was performed to each peak. The calculated parameters
for as-deposited and annealed TCVA films are listed in Table 3.
A comparison of these results shows that all parameters vary in
the band regions, and have a slight change by annealing process.
[
[
[
[
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TCVAthinfilmswerepreparedforthefirsttimeusingthermal
evaporation technique. A comparison of FTIR spectra of powder
and as-deposited thin film forms indicated that the thermal evap-
oration technique is a good one to obtain undissociated TCVA
films. In addition, the IR spectrum of the annealed TCVA film
is similar to the spectra of powder and as deposited film, which
indicated that TCVA film has good thermal stability. According
to the optical absorption spectra, TCVA thin film has a wide
absorption range spectrum in UV–vis region, which is appropri-
ate for application of TCVA thin films in photovoltaic devices.
Furthermore, theanalysisofabsorptioncoefficientrevealedindi-
rect transitions with 1.45 eV as energy band gap.
[
[
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1
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Acknowledgements
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The authors are grateful to the referees for critical comments
on the paper. One of authors, Ahmed A. Darwish, wishes to
thank Sana’a University (Yemen) for the award of a scholarship
for PhD at Ain Shams University.
[
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