Influence of the Deviation from Stoichiometry on Transport Properties of Titanium Oxides Thin Films

Abstract

This study examines the impact of structural defects, resulting from oxygen vacancies, on the electrical conductivity of thin films of nonstoichiometric titanium oxides across a temperature range of 20 to 290 K. It is demonstrated that vacancies significantly influence the transport properties of such systems, as they markedly alter their electronic properties. The characteristic temperatures and densities of states as a function of the deviation from stoichiometry are estimated based on the variable range models of Mott and Efros–Shklovskii. The temperature dependence of electrical conductivity reveals a crossover regime between the Mott and Efros–Shklovskii regimes. The comprehensive explanation of this result is based on the proposed electrical conductivity interpolation formula, in which the pre-exponential factors depend both on the deviation from stoichiometry and on the exponential dependence of temperature derived by Mansfield. Finally, diagrams are proposed to enable the verification of the obtained results with respect to the microscopic parameters of thin films of the nonstoichiometric titanium oxides.