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We present a Ge/MoS2 van der Waals heterojunction photodetector with a short active region constructed using a transfer process. The device exhibits broadband, self-powered, superior device performance within the visible to infrared wavelength (500–1700 nm) operated in a photovoltaic mode. Intriguingly, a sharp increased gain of 10 556 (93) with a varied breakdown voltage of −8.02 V (−6.25 V) under the 700 nm (1550 nm) laser illumination was observed, which was interpreted as the synergistic effect of both soft and avalanche breakdown behavior. These results imply disposable high-sensitivity broadband light-detection potentials with a simple Ge/MoS2 heterojunction, exempting it from the complex and strict construction requirement of conventional avalanche photodetectors. [ABSTRACT FROM AUTHOR]

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]

We demonstrated that Schottky barrier height (SBH) at the metal/CVD-grown MoTe2 interface can be significantly reduced with tunnel contact by inserting a thin Al2O3 layer regardless of the metal work function. The existence of strong Fermi level pinning (FLP) at the metal/MoTe2 interface was verified, while depinning cannot be achieved with Al2O3 insertion. Thus, the fixed charges inside the Al2O3 were proposed to be responsible for the effective SBH reduction in virtue of the eliminated SBH reduction after the post-annealing treatment. This work provides a feasible way to solve the contact issue and favors for the fabrication of high performance MoTe2-based electronic devices. [ABSTRACT FROM AUTHOR]

Recent investigations reveal elemental semimetal (Bi and Sb) contacts fabricated with conventional deposition processes exhibit a remarkable capacity of approaching the quantum limit in two-dimensional (2D) semiconductor contacts, implying it might be an optimal option to solve the contact issue of 2D semiconductor electronics. Here, we demonstrate novel compound Dirac semimetal ZrTe 2 contacts to MoS 2 constructed by a nondestructive van der Waals (vdW) transfer process, exhibiting excellent ohmic contact characteristics with a negligible Schottky barrier. The band hybridization between ZrTe 2 and MoS 2 was verified. The bilayer MoS 2 transistor with a 250 nm channel length on a 20 nm thick hexagonal boron nitride (h-BN) exhibits an I ON / I OFF current ratio over 10 5 and an on-state current of 259 μA μm -1 . The current results reveal that 2D compound semimetals with vdW contacts can offer a diverse selection of proper semimetals with adjustable work functions for the next-generation 2D-based beyond-silicon electronics.