Electrical switching and Mott transition in VO₂

In this paper the problem of the Mott metal-insulator transition in vanadium dioxide driven by an external electric field is considered. Delay time (t_d) measurements have shown that the experimental value of t_d is almost three orders of magnitude lower than the theoretical value, calculated in a simple electrothermal model. This suggests that under non-equilibrium conditions (in high electric fields) electron correlation effects contribute to the development of the insulator to metal transition. The extra-carrier injection from Si into VO₂ was carried out in the structures Si-SiO₂-VO₂ on p-type silicon with ρ = 0.1 Ω cm and a SiO₂ thickness 70 nm. It has been shown that the metal-insulator transition in VO₂ can be initiated by injection, i.e. by the increase of the electron density. The value of the critical density was found to be of the order of the electron density in VO₂ in the semiconducting phase, approximately 10¹⁸-10¹⁹ cm^-3. This confirms that the metal-insulator transition in VO₂ is the purely electronic Mott-Hubbard transition.