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We demonstrated that ternary HfAlO2 amorphous film prepared with common co-sputtering technology can be a suitable gate dielectric for bilayer MoTe2 transistors. The film quality can be improved by optimizing the sputtering process and post-annealing treatment, which is superior to its binary Al2O3 and HfO2 components and satisfies gate dielectric criteria. The bilayer MoTe2 transistors with ∼29-nm-thick HfAlO2 gate dielectric exhibit an Ion/Ioff ratio of over 108 by a low operating voltage, together with a small subthreshold swing ≈ 71.22 mV/dec. These promising characteristics favor the development of high-performance and low-power ultrathin MoTe2-based beyond-silicon electronics. [ABSTRACT FROM AUTHOR]

We demonstrated that the carrier polarity of MoTe2 transistors can be modulated by controlling the channel thickness with NiTe2 semimetal contacts. The multilayer MoTe2 transistors (thickness >7.1 nm) exhibit a symmetric ambipolar conduction, and a transition to unipolar p-type polarity occurs as the channel thickness decreased down to ∼2.3 nm. The position of the semimetal NiTe2 work function was verified to be located at the mid-gap of multilayer MoTe2, and the observed transition was interpreted by a synergistic effect of the channel thickness-dependent band alignment and charge transfer behavior with unique NiTe2 semimetal contacts. [ABSTRACT FROM AUTHOR]