Dependence of VO$_{2}$ thin-film metal-insulator transition on its intrinsic impurities

We present variation in strain, metal-insulator transition temperature ($T_{MIT})$, activation energy ($\Delta E_{a})$, and charge carrier type in the insulating phase of (011) preferred polycrystalline (Poly-) and multidomain (020) epitaxial (Epi-) VO$_{2}$ films grown at different temperature ($T_{S})$, to produce variable intrinsic impurities. Both the Poly- and Epi-VO$_{2 }$behave $n$-type conductivity when grown at relative low $T_{S}$. As $T_{S}$ increases, acceptor density of impurity increases to alter conductivity from $n$- to $p$-type in the Poly-VO$_{2}$, while conductive $n$-type still keeps in the Epi-VO$_{2}$ with increased donor density. Moreover, the strain along monoclinic $a_{m}$ axis dramatically reverses from tensile to compressive in both the Poly- (848 K$