Electrical and Thermal Characteristics of the Insulator–Metal Transition in Crystalline $$\hbox {V}_{2}\hbox {O}_{5}$$ V 2 O 5 Films

Abstract

The electrical and thermal properties with respect to the crystallization in $$\hbox {V}_{2}\hbox {O}_{5}$$ thin films were investigated by measuring the resistance at different temperatures and applied voltages. The changes in the crystal structure of the films at different temperatures were also explored using Raman measurements. The thermal diffusivity of the crystalline $$\hbox {V}_{2}\hbox {O}_{5}$$ film was measured by the nanosecond thermoreflectance method. The microstructures of amorphous and crystalline $$\hbox {V}_{2}\hbox {O}_{5}$$ were observed by SEM and XRD measurements. The temperature-dependent Raman spectra revealed that a structural phase transition does not occur in the crystalline film. The resistance measurements of an amorphous film indicated semiconducting behavior, whereas the resistance of the crystalline film revealed a substantial change near $$250\,{^{\circ }}\hbox {C}$$ , and Ohmic behavior was observed above $$380\,{^{\circ }}\hbox {C}$$ . This result was due to the metal–insulator transition induced by lattice distortion in the crystalline film, for which $$T_{\mathrm{c}}$$ was $$260\,{^{\circ }}\hbox {C}$$ . $$T_{\mathrm{c}}$$ of the film decreased from 260 $${^{\circ }}\hbox {C}$$ to $$230\,{^{\circ }}\hbox {C}$$ with increasing applied voltage from 0 V to 10 V. Furthermore, the thermal diffusivity of the crystalline film was $$1.67\times 10^{-7}\,\hbox {m}^{2}\cdot \hbox {s}^{-1}$$ according to the nanosecond thermoreflectance measurements.