Metal-substitution strategy to control the conductive path in titanium dioxide: ab initio calculations

Revealing the atomic-nature of the conductive path in TiO₂ layer based resistive-switching devices still remains a critical challenge. Metal atoms doping in TiO₂ layer are always considered as an effective way to improve the electronic properties in resistive random access memory. Efforts to clarify the effects of metal atom substitution on the conductive path in rutile TiO₂ have been done by using first-principles calculation. The dependence of the conductive path on the substitution of Ag/Cu/Al/Hf/Ta/V adjacent to the ordering oxygen vacancies or away from them has been studied in detail to elucidate the formation mechanism of conductive path. Theoretical investigation demonstrates that Hf or V substitution where it occurs adjacent to the oxygen vacancies benefits electrons aggregation among Ti-ions. Such electrons aggregation, which is one type of the conductive path in TiO₂, will be prompted by Ti-t2g orbital electron. The dependent relation of the conductive path on the substitution of Ag/Cu/Al/Hf/Ta/V will be an important factor to optimize future resistive random access memory.