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FIZIKA A 4 (1995) 1, 17-31
 
TRANSPORT PROPERTIES OF PbTe9.7Sb0.3THIN FILMS
ZEINAB S. EL-MANDOUH and MOHAMED EL-SHABASY
Physics Department, National Research Center, Cairo, Egypt
Mail to: Physics Department, Faculty of Science,
El-Minia University, El-Minia, Egypt
Received 11 November 1993
Revised manuscript received 18 November 1994
Thin films of (PbTe)9.7Sb0.3 per weight of
different thicknesses have been prepared on quartz substrate by vacuum thermal
evaporation. Heating-cooling cycles indicate an increase of resistivity with successive
cooling cycles. These observations can be explained by considering the desorption of
absorbed gas molecules and creation of defects during the heating process. Isothermal
annealing effect was studied. Plots of logarithm of resistivity versus temperature were
analyzed to derive the activation energy for the defect formation. The apparent value of
the energy was 0.18 eV, i.e. about a half of the activation energy for conduction. The
activation energy for conduction and resistivity are thickness dependent. The optical
spectrum of (PbTe)9.7Sb0.3 in the infrared
region was measured. From the spectrum, we derived the values of the direct and indirect
energy gaps of 0.29 and 0.19 eV, respectively.
UDC 538.93
PACS 73.61.Le, 78.66.Li
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