Low temperature dielectric behavior and ac conductivity in metal-containing chalcogenide Ge 2S 3 films

Abstract

Two systems of ternary compositions of chalcogenide-containing metals were prepared by adding metal whether Cu or Cd to a chalcogenide Ge 2S 3 binary system. Capacitance, Debye dielectric response and ac spectroscopic measurements of these compositions: Ge 2S 3, (Ge 2S 3) 0.95Cu 0.05 and Cd 0.5Ge 2S 3 films were, respectively, investigated in a comparative study, over the frequency range from 100 Hz to 100 kHz and within the temperature range from 153 to 263 K. The frequency and temperature dependence on the loss tangent factor and the dielectric constant showed a Debye dielectric relaxation process. Using Debye relation, the distribution factor ( s′−1), the dielectric constant ( ɛ′), the most probable relaxation time ( τ) and the barrier height ( W) were estimated for the binary and the metal-containing chalcogenide systems. The capacitance measurements are found to obey the scaling relation C= Aln( Tω −1), which suggests a relaxation tunneling conduction mechanism. In addition, the analysis of the results suggests that the electronic conduction on adding Cd or Cu to the chalcogenide Ge 2S 3 films occurs via correlated barrier hopping of electrons. On the other hand, at lower temperatures, there is a deviation in the conduction mechanism from the predictions of the correlated barrier-hopping model.