Abstract:
Abstract
In this study, first the alloy of copper selenide was prepared by
quenching technique. After that copper selenide and cadmium sulphide
thin films are prepared by using thermal evaporation technique. The thin
films have been grown on clean glass and ITO substrates. The annealing
effects on the structural, optical and electrical properties of the films
which have been studied.
The results of XRD showed that the copper selenide alloy was
polycrystalline in nature with multiphase of copper selenide, the dominate
phase was CuSe2 with cubic structure and preferred orientation (221).
The cadmium sulfide films were single crystalline, have cubic structure
with orientation (111) plane for as-deposited and annealed films. Copper
selenide films show polycrystalline nature for as-deposited and annealed
films, the Cu3Se2 phase with tetragonal structure and preferred
orientation (101) plane was dominate in the as-deposited film while the
CuSe2 phase with cubic structure and preferred orientation (221) plan
was dominate in annealed film. "Scherrer’s formula" has been used to
calculate the crystallite size and it is found increases after annealing for
both films. ""AFM" outcomes show that increase in surface roughness and
(RMS) for both annealed films, in addition the grain size of cadmium
sulphide film increases in annealing but decreases for copper selenide
film. SEM results show that the copper selenide powder have a compact
structure composed of single type.
The absorbance and transmittance curves were recorded in the range
of (400- 1100) nm to investigate the optical characteristics. The results
have shown that the cadmium sulphide and copper selenide films have a
good transmittance in visible and NIR region. The absorption coefficient
and refractive index were calculated too. The energy gap for allowable
direct electronic, transition was estimated using Tauc’s model. The
energy gap was decrease from (2.45 eV) to (2.41 eV) for cadmium
sulphide thin film when annealed, and for copper selenide was increase
from (2.27 eV) to (2.32 eV) after annealed.
The electrical properties included D.C, hall effect measurements,
and (I-V) characteristic of solar cell. From D.C. measurements, It has
found that the D.C conductivity of cadmium sulphide thin film was
increase after annealing while decrease for copper selenide thin film after
annealing. All films have two transport mechanisms of free carriers and
there was two activation energies for as- deposited and annealed films.
Hall measurement results showed that the thin films of cadmium sulphide
are n-type while copper selenide thin films are p-type.
On the other hand, “Voc, ISC, Rs , Rsh , FF and efficiency” of the solar
cell have been measured. The solar cell parameters were found by using
(I-V) tester system under illumination. The results show that no
efficiency found for copper selenide/ cadmium sulphide /ITO solar cell.
