All-van-der-Waals Barrier-Free Contacts for High-Mobility Transistors (vol 33, 2109521, 2021)

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 approximate to 1304 cm(2) V-1 s(-1). The formation of such contacts can be attributed to the higher work function of approximate to 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.