Effect of local perturbations on the semiconductor-metal phase transition

The effects of various surface factors on the semiconductor-metal phase transition in $VO_2$ films were experimentally studied. It has been shown that adsorption of donor $Н_2О$ and $NH_3$ molecules lowers the phase transition critical temperature $Т_с$, adsorption of acceptor $O_2$ molecules exerts no effect on $Т_c$, while adsorption of oxygen ions increases $Т_с$. UV irradiation causes degradation of the semiconductor-metal phase transition. The effect of phase transition photosensitization has been discovered. The experimental data obtained and the data of other researchers on the effects of external factors on the phase transition have been analyzed in terms of the phonon anharmonism model developed by the authors.