THERMAL TRANSFORMATIONS OF Ga-MoO3 SYSTEM

Abstract

Transformations in nanoscale Ga–MoO3 systems are studied with methods of optical spectroscopy, microscopy, gravimetry, depending on the thickness of Ga (d =2 –96 nm) and MoO3 (d = 7–62 nm) films, the temperature (473–773 K) and the heat treatment time. It was shown that the absorption spectra of the Ga-MoO3 systems in the short-wavelength region of the spectrum (λ = 300–500 nm) as the thickness of gallium films decreases are determined by the absorption of MoO3 films, and in the long-wavelength region of the spectrum (λ = 500–1100 nm), the absorption bands of gallium films appear. The kinetic dependences of the degree of conversion of MoO3 and gallium films have been calculated, constructed and compared. It has been established that an increase in the thickness of MoO3 films in Ga–MoO3 systems at a constant processing temperature leads to a decrease in the degree of transformation of the center of [e∙(V_a )^(++)∙e] MoO3 films, while an increase in temperature at a constant thickness of MoO3 films contributes to its increase. It is shown that the rate of transformation of the center of [e∙(V_a )^(++)∙e] MoO3 films in Ga–MoO3 systems is higher than in individual MoO3 films. The contact potential difference for Ga, MoO3, and photo-emf of Ga–MoO3 is measured, which corresponds to a positive sign from the MoO3 layer. A diagram of the energy bands of Ga–MoO3 systems is constructed. A model is proposed for the thermal transformation of MoO3 films in Ga–MoO3 systems, including the redistribution of equilibrium charge carriers on the contact, the formation of the center [(V_a )^(++)∙e] during the preparation of the MoO3 film, its transformation in the creation of Ga–MoO3 systems at the center [e∙(V_a )^(++)∙e], the thermal transition of the electron to the level of the center [(V_a )^(++)∙e] with the formation of the center [e∙(V_a )^(++)∙e].