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

Abstract

Abstract 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.