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 TiOx interlayers positioned between the MoSe2 channel and Ti/Al contacts. Transmission electron microscopy analysis revealed the presence of TiOx at the MoSe2/Ti interface. While MoSe2 transistors exhibited poor device performance in the absence of a TiOx interlayer, the introduction of a TiOx 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 TiOx interlayers. These results underscore the feasibility of incorporating TiOx interlayers to enable the use of conventional Al contacts in MoSe2 transistors, delivering significant implications for enhancing the performance of transition metal dichalcogenide transistors. [Display omitted] •Incorporation of TiOx interlayers to enable Al-contacted MoSe2 transistors.•One step implementation of TiOx/Ti/Al contacts in high vacuum for MoSe2 transistors.•Superior transistor performance enhancement to those without TiOx interlayers.•Best transistor performance in MoSe2 transistors with a 7.5-nm-thick Ti interlayer.