GROWTH AND CHARACTERISTIC OF AMORPHOUS NANO-GRANULAR TeO₂–V₂O₅–NiO THIN FILMS

Abstract

TeO2–V2O5–NiO thin films were deposited using thermal evaporation from 40TeO2–([Formula: see text])V2O5–yNiO ([Formula: see text]–30[Formula: see text]mol%) target. Structural analysis of the films was identified by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The amorphous TeO2–V2O5–NiO films have nanosized clear grain structure and sharp grain boundaries. DC conductivity and current–voltage (I–V) characteristic of TeO2–V2O5–NiO thin films were measured in the temperature range of 300–423[Formula: see text]K. As nickel oxide (NiO) content increases, the DC conductivity decreases up to two orders in value ([Formula: see text]–[Formula: see text][Formula: see text]S[Formula: see text][Formula: see text][Formula: see text]cm[Formula: see text]. Temperature dependence of conductivity is described using the small polaron hopping (SPH) model as well. Poole–Frenkel effect is observed at high external electric field. The optical absorption spectra of the TeO2–V2O5–NiO thin films were recorded in the wavelength range of 380–1100[Formula: see text]nm. The absorption coefficient revealed bandgap shrinkage (3.01–2.3[Formula: see text]eV) and band tail widening, due to an increase in NiO content. Energy dispersive X-ray spectroscopy (EDX) was used to determine elemental composition. In TeO2–V2O5–NiO thin films, the NiO content is around fifth of the initial target.