Substrate Effect On Structural, Microstructural And Elemental Microcomposition Of Vanadium Dioxide Thin Film

Vanadium dioxide (VO2) is a phase change material with a metalinsulator transition (MIT), occurring around 68°C with several order of change in its electrical resistance. In this work, structural and microstructural studies have been carried out in order to understand the substrate effect on VO2 crystallographic growth properties as well as on transition quality. VO2 thin films were deposited by pulsed laser deposition (PLD) technique on a 2 μm thick oxide SiO2 buffer layer for the first sample (VO2/SiO2/Si) and on a 200 nm thick gold buffer layer for the second sample (VO2/Au). Microstructural and microcomposition analysis were performed using scanning electron microscopy and related energy dispersive X-ray analyses (SEM-EDX). Results show a variation in VO2 grain shape depending on the substrate type. “Trapezoid-like” shape grains are covering the surface of gold (Au) thin layer, and elongated shape “nanoplatelets-like crystals” are covering the (VO2/SiO2/Si) surface due to a preferential 2D layered growth. In addition, the structural characterizations show that VO2 deposits promote a preferential growth direction of (011). The substrate type strongly affects the VO2 growth rate. This work could help the optimization of metal-insulator transition (MIT) materials quality that have many applications ranging from sensor devices that need sharp transition slope to storage devices requiring a large hysteresis width.