الفهرس 
CHAPTER ONE. Introduction and Literature ReviewOnly 14 pages are availabe for public view
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Abstract
Transparent conducting CuAlS2 thin films have much attention
due to their various technological applications including solar cells, flat
panel displays, light emitting diodes, optoelectronics polycrystalline thin
films and optical frequency conversion in all solid state based tunable
laser systems. CuAlS2 thin films are considered as important optical films
due to their high refractive index, high band gap, transparency over a
wide spectral range, adjustable electrical conductivity, perfect chemical
stability, and environmental nontoxicity. The triple compound CuAlS2
belongs to the I-III-VI2 family of semiconductors with chalcopyrite-type
structure. As well known, there are a variety of physical and chemical
methods were used to obtain CuAlS2 thin films for many applications.
There are many research and manufacturing sectors prefer to use physical
vapor deposition (PVD) techniques in the deposition process of ceramic
coatings for multiple applications. Vacuum thermal evaporation is a
modern PVD process and largely engaged for industrial application due
to its major advantage of low contamination of the deposited thin films,
and improved control of deposition rate. This method prevents arcing and
producing high-quality film beside good adhesion to different metallic
and nonmetallic substrates.
The current proposed work was focused on fabricating bulk
CuAlS2 samples by powder metallurgy technique (P/M) at compacting
pressure (350MPa), sintering time (2hr) and different sintering
temperature (100, 150, 200, 250 and 300°C). These bulk sample used to
prepare CuAlS2 thin films by vacuum thermal evaporation technique. The
CuAlS2 thin films were tested and characterized using X-ray diffraction,
scanning electron microscopy (SEM) provided with with EDS analysis.
Wear and friction measurements using oscillating ball-on-disk tribometer
were used. Contact angle analyzer for wettability measurements has been
used. Slurry erosion testing using a slurry whirling arm rig is used.
III
Corrosion resistance measurements were performed using VersaSTAT4.
UV–visible-IR spectrophotometer for optical measurements has been
used. Electrical resistivity and Seebeck coefficient were measured using
the designed circuit of two probe system.
The main goal of this work is to study the effect of the sintering
temperature of the bulk compacted powder sample on the microstructure,
mechanical, tribological, optical, electrical, and electrochemical
properties of the CuAlS2 thin films which were fabricated by a thermal
evaporation technique.
XRD analysis of the deposited CuAlS2 thin film revealed the
formation of the CuAlS2 phases with prefered orientation (0 0 8).
The wear rate and corrosion resistance were improved for CuAlS2
films with increasing the sintering temperature. The wear rate decreased
from 1.2x10-4 mm3/Nm at sintering temperature 250°C to 5.8x10-5
mm3/Nm at sintering temperature 300°C. Moreover, the friction
coefficient decreased with increasing the sintering temperature from 0.49
for the sample of 150°C to 0.41 for the sample of 250°C. Slurry erosion
of the CuAlS2 films give high erosion values because of the impact angle
is small. The corrosion resistance, impedance, and Mott–Schottky plot of
CuAlS2 thin films were improved with increasing the sintering
temperature. Further, the optical data showed an increase in the
transmittance and a decrease in the reflectance of CuAlS2 films as the the
sintering temperature increases in the visible (VIS) and infrared (NIR)
regions. The maximum value of transmittance ≈ 87% in the near infrared
region (NIR) at 200, and 250°C and ≈77% in the visible region (VIS)
was obtained for sintering temperatures 200°C. Also, the reflectance
decreased with increasing sintering temperatures from 18% at sintering
temperatures 100°C to 6% at sintering temperatures 200, and 250°C in
the near infrared region (NIR). The optical bandgap of the CuAlS2 thin
films has been decreased from 2.76eV with increasing the sintering
temperature at 100°C to 2.63eV at 300°C. On the other side, the electrical
properties of the CuAlS2 thin films have been improved with increasing
the sintering temperature. Whilst, the electrical resistivity (ρ) is decreasedIV
from 49.28Ω.cm at sintering temperature 100°C to 0.52Ω.cm at sintering
temperature 250°C. Also, is the electrical conductivity (σ) increased with
increasing the sintering temperature to reach the maximum value of 1.92
Scm-1 at sintering temperature 250°C. The variation of the thermoelectric
power (S) as a function of the temperature was measured on CuAlS2
thin films. The plot shows that the values of the Seebeck coefficient (S)
increase with increasing the sintering temperature, revealing the
semiconducting nature of the samples. Also, the maximum value of the
Seebeck coefficient reached -496μV/K at sintering temperature of 250°C
at room temperature. The values of the Seebeck coefficient of all
samples are negative at room temperature implying that the samples are
n-type in nature.