Effect of substrate temperature on micro-structural, optical and electrical properties of V2O5 thin films

Abstract

Vanadium pentoxide (V 2 O 5 ) thin films have been prepared onto ITO coated flexible Kapton substrates by electron beam evaporation technique. The influence of substrate temperature on the structural, morphological, optical and electrical properties has been investigated. The XRD results reveals that the films prepared at lower temperatures are amorphous in nature and the films prepared at 300 o C is exhibited predominant (001) orientation with an orthorhombic crystal structure. AFM study showed that the grain size varies from 80 nm to 150 nm. The optical studies revealed that the transmittance decreased with increasing substrate temperature. The optical absorption coefficient '' determined from the experimentally measured transmittance and reflectance data for V 2 O 5 films was found to give a better fit for the exponent n = 3/2 suggesting the direct forbidden transitions with an estimated optical band gap of 2.31 eV for the films prepared at 300 o C. The electrical conductivity has been observed to be increased from 2 x 10 -6 S/cm to 3 x 10 -2 S/cm by varying temperature from 30 o C to 300 o C. The electrochemical experiments exhibited the discharge capacity of about 60 μAh/(cm 2 -μm) for the films deposited at 300 o C. Copyright