الفهرس 
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Abstract
The study of thin films of materials in recent years has greatly
interest of material scientists due to discovery of new device applications in
industry and medical science. CulnSZ was chosen because the constituent
materials are plentiful and easily obtained in the required purities.
In the present work, a brief account about the equipment and the
techniques employed for the production of CulnSZ thin films by two
methods (chemical bath deposition and thermal evaporation under high
vacuum) . This is followed by describing the procedure of measuring the
characteristics of the films obtained by the above techniques. The techniques
employed for estimating the film thickness, the microstructure and
opto-electronic properties were given. The effect of heat treatment on these
properties and the theoretical calculation of the relative intensity of the
diffraction lines of CulnSZ films were studied. A comparison of the
experimental , ASTM and calculated relative intensities show little
difference.
The chemical deposition technique give x-ray powder diffraction of
CulnSZ single phase with chalcopyrite structure. The film thickness
increased by increasing the number of runs in fresh solution. The x-ray
diffractogram of these films show a difference between thin and thick films.
Thin films still amorphous or composed of very fine grains up to - 500 I( •
The heat treated of these films (heating temperature - 673 I() show a
pronounced diffraction peak corresponding to the (l1Z) plane besides (013),
(004) and (OZO) planes. These results indicate that the crystallinity of the
films has been improved by the annealing treatment. While thick films
(more runs) show peak of low intensity from the second phases CUS, In2S3
besides a strong (112) plane for CuInS2 when heated at - 573 k.’ • But at high
temperature (- 673 k.’), only CuInS2 planes appeared. It was noticed from
all the x-ray diffractogram that, - 500 I(was required for heat treatment to
complete convert the amorphous film to polycrystalline structure. In the
range _ 500-700 k.’ the compound was stable, while at higher temperature >
700 k.’ the films showed considerable degradation . The surface morphology
of the CuInS2 films of different thicknesses was investigated using scanning
electron microscopy (SEM). It was noticed (from the plates of the
morphology) that by increasing the film thickness and also the annealing
temperature, the uniform distribution of the grains was observed.
In comparison, thermal evaporation technique was used to prepare
CuInS2 films from the constituent elements. The x-ray diffraction of the
powder show single phase CuInS2 with chalcopyrite structure. The films
prepared from this powder show amorphous structure up to - 473 k.’. At high
temperature of heat treat - 673 k.’ reveal (112) plane besides other planes of
chalcopyrite CuInS2. The scanning electron microscopy of these films show
that, the as-deposited films of different thickness demonstrate a small grains
and non-uniform distribution. The heat treatment of these films at different
temperatures show an accumulation of grains or the grains are inlarged.
The optical density and the corresponding transmission spectrum of
CuInS2 films were recorded over the spectral range from 300 _. 900 nm
using double beam spectrophotometer. The values of the refractive index,n,
, absorption index ,k, absorption coefficient, a, and the optical energy
gap, Eg, were calculated from the transmission data of CuInS2 films which
deposited from chemical and thermal techniques. It appears from the figures
of the thermal deposited specimens (non-heated) that, the optical band gap
Eg is dependent on sample thickness. By heating the samples at 623 I( and
700 1(, the value of Eg is around 1.52 eV, which is less than the energy gap
value of the non-heated layers. But the optical energy gap of the chemical
layers is 1.496 eV for heated and non-heated thick films (5 run). These
values are lower than the values reported for the evaporated thin films.
Electrical properties of CuInS2 films prepared by chemical
deposition and thermal evaporation techniques were studied using direct
current (d.c) and alternating current (a.c). The (d.c) measurements of
chemically deposited films show that, the films has low resistance (R) at
room temperature (1’). The variation of , R versus lIT was not stable for
the first heating run of measurement. Cooling run of the first run was not
reversed on the same curve, the film resistance was increased as ”1’”
decreased and a complete reaction was existed. The energy gap [ Eg _ 1.55
eV] was calculated, and was found to decrease as the film thickness
increases.
In contrast, thermal as evaporated films show a high resistance at
room temperature, the decrease of resistance with increasing temperature
for the first run in a stable behaviour with two slopes. The energy gap
calculated from the high temperature region (intrinsic), E
g
_ 1.5 eV. A
reduction in resistance with cooling was achieved, the stable curve with one
slope yield an activation energy Ed - 0.6 eV. The heat treatment of films at
different temperatures show no difference with the cooling run i.e the
electrical properties of the film was changed by heat treatment.
A.C measurements was used to obtain several electrical constants
of the solids, also, the equivalent circuit of the samples . The impedance
/Z*I was studied as a function of the frequency ” f”, this study shows
difference between thin and thick films. The equivalent circuit for these
samples were postulated. The imaginary part and real part of IZ*I; Z” and
Z’ was also studied. In the same way the relations were also differes
between thin and thick films. from these relations, ” R
g
” , ” C
g
” (the grain
or bulk resistance and capacitance); ”Rgb”, ” Cgb ” ( the grain boundary
resistance and capacitance) and other parameters could be calculated.