TiO2/Cu/TiO2 (TCT) multilayers were deposited
by dc pulsed magnetron sputtering on glass substrates for the
possible use as transparent conducting oxide (TCO). The
thicknesses of copper (
Cud) interlayers were 0, 8, 10, 12, 13
and 15 nm. The changes in structural, optical and electrical
properties of the TCT multilayers have been investigated as a
function of Cud.
XRD examination revealed that, all studied
TCT multilayers have rutile TiO2
crystalline structure with
different orientations, whereas no peaks have been indexed
for the Cu. The refractive index (at 650 nm) of the TCT
multilayers decreased from 2.39 to 1.90 and the optical band
gap values decreased from 3.77 ± 0.02 to 3.66 ± 0.02 eV as
the thickness of the Cu interlayer increased from 8 to 15 nm.
It has been found that the electrical resistivity of TCT multilayers
decreased from 1.4 × 10−4 to 3.2 × 10−5 Ω cm with
increasing Cu interlayer thickness from 8 to 15 nm. The
TCT film with 10 nm Cu interlayer has a sheet resistance of
13.7 Ω/sq, an average transmittance value of 87.1% (in the
wavelength ranging from 500 to 800 nm) and highest figure
of merit value of 1.84 × 10−2 Ω−1. Accordingly it can be
considered as superlative TCT film which can be potentially
used as transparent conductor electrode for solar cells and
other optoelectronic applications.