On high-field conduction and I–V measurements in quaternary Se–Te–In–Pb nano-chalcogenide thin films

Abstract

In this paper, multi-component Se79-xTe15In6Pbx (x = 0, 1, 2, 4, 6, 8 ,and 10 at.wt.%) nano-chalcogenide alloys were prepared by using melt quenching technique and their electrical properties and sub-micron structural features have been reported and discussed in detail. Sharp characteristic peaks in x-ray diffraction (XRD) spectra signify nano-range of each alloy under investigation and validated by field emission scanning electron microscopy (FESEM). The thin films of investigated nano-chalcogenide alloys were deposited on glass substrates by thermal evaporation technique. In-depth analysis of DC conductivity for studied nano-chalcogenide alloys was carried out in the temperature range 303–333 K and in the voltage range 0–150 V, to realize the conduction mechanism. I–V characteristics illustrate ohmic behavior in the voltage range 0–50 V while at high voltage non-ohmic behavior is detected. Moreover, pre-exponential factor (σo) along with activation energy (ΔE) deduced from the variation of DC conductivity with temperature, which reveals that thermally assisted tunneling of charge carriers among the localized states occurs in band tails responsible for conduction in the analyzed systems. The detailed analysis indicates that SCLC theory is not appropriate to describe the conduction process, as ln(I/V) against V plots is almost straight, although slope of these plots does not reduce linearly with temperature. The linear relation among ln(I) against V1/2 demonstrates that the conduction mechanism is either Poole–Frenkel type or Schottky emission. The obtained outcomes demonstrate that Poole–Frenkel conduction mechanism is most appropriate to describe the conduction. The deduced values of activation energy are less than 0.98 eV, which once again validated the presence of Poole–Frenkel type conduction in the examined composition. The deduced results are further corroborated by photoluminescence studies.