Thermally stable Bi₂Te₃/WSe₂ Van Der Waals contacts for pMOSFETs application

Novel van der Waals (vdW) contacts formed by layered Bi₂Te₃ are found effective in improving the performance of WSe₂ pMOSFETs. As compared with conventional transition metal-based Ni/Au S/D contacts, over 10³ times on-state current improvement is achieved. vdW interface formation between Bi₂Te₃ and WSe₂ is confirmed by X-ray diffraction analysis and scanning transmission electron microscope observation. An atomically flat Bi₂Te₃/WSe₂ vdW interface, where the number of defects could be reduced as small as possible, contributes to the suppression of Fermi-level pinning caused by defect-induced gap states. Moreover, the semimetal-like characteristics of Bi₂Te₃ are also effective in minimizing the impact of metal-induced gap states. These features offer WSe₂ pMOSFETs with exceptional S/D junction characteristics, including suppressed off-state leakage and a higher on-off ratio. In addition, it is found that WSe₂ pMOSFETs with Bi₂Te₃ S/D contacts have excellent thermal stability, maintaining device performance even after 400 °C annealing, which is very promising for CMOS back-end-of-line application. The layered tellurides, reconciling low contact resistance and high thermal stability, are promising, particularly from the perspective of their application in the manufacturing process.