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Abstract
Highly oriented CdTe thin films were successfully prepared by thermal
resistive current technique ( Physical Vapor Deposition PVD) under vacuum
~ 10-5 torr. Relatively large number of CdTe thin films were prepared to cover a
wide range of investigated parameters, namely, substrate temperature (T sub),
source temperature (Ts) and film thickness (t). The films were deposited onto
glass substrate while the subsrrate temperature was varied in the range of 473 to
623 oK. The films thicknesses were controlled during the evaporation by a pre-
calibrated quartz thickness monitor. Two different source temperatures
(evaporation temperature, Ts =773 and 973 OK, were chosen for the film
preparation.
It was found that the CdTe films adhered firmly to the substrate and their
colour changed gradually from light brown to dark gray as the substrate
temperature increases.
The structural, electrical and optical properties of CdTe thin films were
studied under different temperature (300-423 OK). During electrical and optical
measurements, the sample was under vacuum 10-3 torr. The obtained results
which were interpreted and discussed lead to the following conclusions:
The films which were deposited at substrate temperature in the range of
473 to 623 OK (while both the film thickness, 1080 nm, and the source
temperature, 973 OK were kept constant) showed a highly preferred orientation
of (11 1) plane parallel to the substrate surface. The degree of the preferred
orientation increased with increasing T sub,
The increase of the conductivity o of the CdTe films with increasing the
substrate temperature is attributed to the growth of larger grain sizes which in
turn increases the electron mean free path and reduces the scattering effect.
.