High Field Conduction in Thin Films of a-(Ge_{.20}{Se0}_{.80})_{1-x}{Pb}_x Glassy Alloys

Authors: RACHNA SINGH, SANTOSH KUMAR

Abstract: The present paper reports d.c. conductivity measurements at high electric fields in vacuum evaporated amorphous thin films of (Ge_{.20}Se0_{.80})_{1-x}Pb_x (where x = 0, 0.02, 0.04, 0.06 and 0.10) glassy alloys. Current-Voltage (I-V) Characteristics have been measured at various fixed temperatures. In these samples, at low electric fields, ohmic behavior is observed. However, at high electric fields (E \sim 10^4 V/cm), non-ohmic behavior is observed. An analysis of the experimental data confirms the presence of space charge limited conduction (SCLC) in the glassy materials studied in the present case. From the fitting of the data to the theory of SCLC, the density of defect states (DOS) near Fermi level is calculated. It is found that the DOS is increasing with increase in concentration of Pb in pure binary Ge_{0.20}Se_{0.80} glassy system. The peculiar role of third element Pb as an impurity in the pure binary Ge_{0.20}Se_{0.80} glassy alloy is also discussed.

Keywords: Thin films, Chalcogenide glasses, SCLC, DOS

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