Engineering TiOx interlayers in high vacuum for Al-contacted MoSe2 transistors

We present an enhanced performance of MoSe₂ transistors via sequentially depositing Ti and Al in high vacuum to establish TiO_x interlayers positioned between the MoSe₂ channel and Ti/Al contacts. Transmission electron microscopy analysis revealed the presence of TiO_x at the MoSe₂/Ti interface. While MoSe₂ transistors exhibited poor device performance in the absence of a TiO_x interlayer, the introduction of a TiO_x interlayer yielded a notable transistor performance, including an on/off ratio of ∼10⁵, a field-effect mobility of ∼40 cm² V⁻¹ s⁻¹, and a contact resistance of ∼100 kΩ μm. These enhancements were attributed to the beneficial effects of Fermi level unpinning and interfacial doping facilitated by TiO_x interlayers. These results underscore the feasibility of incorporating TiO_x interlayers to enable the use of conventional Al contacts in MoSe₂ transistors, delivering significant implications for enhancing the performance of transition metal dichalcogenide transistors.