الفهرس 
General Background
Transparent Conducting Oxide MaterialsOnly 14 pages are availabe for public view
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Abstract
In the recent years, Zinc oxide (ZnO) have received considerable attention due to
the excellent electrical, optical and structural properties, ZnO thin films have wide
applications as transparent electrodes, gas sensors, light emitting diodes (LED’s),
laser systems and hetero-junction solar cells etc, also due to its non toxicity and
abundance. ZnO has a band gap value of 3.42 eV at 300 K, and as a result of
oxygen deficiency and/or zinc interstitials shows intrinsic n-type conductivity. Its
corresponding crystalline structure is hexagonal wurtzite type with lattice constants
c=5.205 Å and a=3.249 Å.
Thin films of ZnO have been deposited by using several deposition techniques,
such as spray pyrolysis (SP), vacuum evaporation, chemical vapor deposition
(CVD), chemical bath, magnetron sputtering, and pulsed laser deposition (PLD).
The spray pyrolysis is one of the attractive techniques for film deposition because
of low equipment cost, simple and safe technique, non vacuum requirement, low
temperature processing, and the possibility of preparing large area. Also, the thin
films by spray pyrolysis technique have good homogeneity.
In order to obtain high conductive and transparent ZnO thin films, impurities from
Group III are commonly added. Among these elements only Indium has been
proved successful over the rest of Group III elements, as ZnO:In thin films with
resistivity values of the order of 4×10−3 Ω .cm . It is worthy to mention that among
all the III Group, Al is a cheap, abundant and non-toxic material and can be an
ideal candidate in replacing In if optimization of the process deposition can be
reached.In recent thesis we report the effect of change in the deposition temperature (350 –
500 ˚C) and Al concentration in the starting solution (0-5 wt. %) on the structural,
compositional, morphological, optical and electrical of sprayed ZnO and AZO thin
films.
XRD data show that the deposited films are polycrystalline with hexagonal
structure. As the substrate temperature increase, the intensity of the (002) peak
increases. All films exhibit highly transmittance up to 90 % in the visible region.
The resistivity of ZnO films was found to decreases with the substrate temperature
increase, the lowest resistivity value 1.14 Ω.cm was observed for ZnO film
prepared at 450 ˚C.
XRD revealed that AZO thin films were polycrystalline with hexagonal structure,
the intensity of (002) peak decrease with Al ratio increase. All films exhibit highly
transmittance up to 85 % in the visible region. AZO film with doping ratio (2 wt.
%) show minimum electrical resistivity 8.61×10-3 Ω.cm ,Carrier concentration
41.3×1019cm-3 and carrier mobility 23.1 cm2/Vs.
Key Word:
Transparent Conducting Oxide (TCO), Zinc Oxide (ZnO) Thin film, Zinc Oxide
doped Aluminium (AZO), Spray pyrolysis, Structure study, Optical study,
Morphological study and Electrical study.