Abstract
TiO
2 thin films were prepared under various conditions by using a reactive RF sputtering technique. The structural, optical and electrical characteristics of the films have been investigated. All as-deposited films were amorphous. After annealing at
T
>
673
K, the crystallinity of the observed tetragonal anatase phase appeared improved. The optical band gap, determined by using Tauc plot, has been found to amount to 3.38
±
0.03 and 3.21
±
0.03
eV for the direct and indirect transition, respectively. Also the complex optical constants for the wavelength range 300–2500
nm are reported. Using the two-point probe technique, the dark resistivity has been measured as a function of the film thickness,
d. The resistivity,
ρ, of the samples has been found to decrease markedly with increasing thickness, but only for
d
<
100
nm. The behaviour of
ρd versus
d was found to fit properly with the Fuchs and Sondheimer relation with parameters
ρ
o
=
4.95
×
10
6
Ω
cm and mean free path,
l
=
310
±
2
nm. The log
ρ versus 1/
T curves show three distinct regions with values for the activation energy of 0.03
±
0.01, 0.17
±
0.01 and 0.50
±
0.02
eV, respectively.