Ultrathin 2D semiconductor devices are considered to have beyond-silicon potential but are severely troubled by the high Schottky barriers of the metal-semiconductor contacts, especially for p-type semiconductors. Due to the severe Fermi-level pinning effect and the lack of conventional semimetals with high work functions, their Schottky hole barriers are hardly removed. Here, an all-van-der-Waals barrier-free hole contact between p-type tellurene semiconductor and layered 1T'-WS2 semimetal is reported, which achieves a zero Schottky barrier height of 3 ± 9 meV and a high field-effect mobility of ≈1304 cm2 V-1 s-1 . The formation of such contacts can be attributed to the higher work function of ≈4.95 eV of the 1T'-WS2 semimetal, which is in sharp contrast with low work function (4.1-4.7 eV) of conventional semimetals. The study defines an available strategy for eliminating the Schottky barrier of metal-semiconductor contacts, facilitating 2D-semiconductor-based electronics and optoelectronics to extend Moore's law.
Keywords: Fermi-level pinning; Schottky barrier; all-van-der-Waals contacts; metal-semiconductor contacts; transistors; van der Waals semimetals; work function.
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