In this paper samples of poly vinyl chloride PVC ,pure, irradiated
with Gama rays, were prepared by casting method in room
temperature and light, and under atmosphere pressure.
It was observed from this research that irradiation made real effect
on some of the studied optical properties, the irradiation increased
the transmittance while the electronic transitions kind remained
indirect before and after the irradiation.
CdTe Thin films were deposited on glass substrates by thermal evaporation
method. The geometric thickness was calculated using interferometric method
based on reflectance curve recorded with the spectrophotometer. The XRD
analysis and optical char
acterizations of CdTe films with different optical
thicknesses reveals that the structure of the films is polycrystalline with
preferential orientation (111). The structure constant (a), crystallite size (D),
dislocation density (δ) and strain (ε) were calculated, and it is observed that the
crystallite size increases but micro-strain and dislocation density decreases with
increases in thin film thickness. The overall absorbance has been increased with
the film thickness and the direct band gap was obtained. It decreases with the
increase in the thickness of the films.
In this paper we present the preparation of PbS nanocrystalline thin films
using Chemical Bath Deposition (CBD) technique. We have performed this
work in order to study the photoconductivity of PbS semi-conductor thin films.
The details of the pre
paration method are described. Thickness of deposited
films has been determined using mechanical and optical methods. From the
optical absorption measurements we have determined the band gap values.
Using the first approximation parabolic bands model and the obtained values
of band gaps, we have determined the size of PbS nanocrystallites. Also, we
have investigated the electrical and photoelectrical behaviors of the PbS films.
Our study shows that the size of PbS thin films nanocrystallites affects the
photoconductive properties of the material. Furthermore, investigations show
that there are two different sizes of grains located in two different layers, the
first one, with grain’s size of about 25nm, concerns the part of PbS deposited
directly on the glass substrate and the second layer, with grain’s size of about
70nm, concerns the PbS deposited on the first layer.
CdTe Thin films were deposited on silicon substrates by thermal
evaporation method. The geometric thickness was calculated using
interferometric method based on reflectance curve recorded with the
spectrophotometer. The Reflection of High-Energy E
lectron Diffraction
(RHEED) patterns and XRD analysis reveals that the structure of the films are
polycrystalline with preferential orientation (111). The structure constant (a),
crystallite size (D), dislocation density (δ) and strain (ε) were calculated, and it
is observed that the crystallite size increases but micro-strain and dislocation
density decreases with increases in thin film thickness. The composition of the
samples was determined by Energy Dispersive X-ray Analysis (EDX) and it is
found that the wt.% of Cd increases and the wt.% of Te decreases with the
increases of film thickness due to the re-evaporation of Te.
