Thermally stable BiTe/WSe Van Der Waals contacts for pMOSFETs application.

Novel van der Waals (vdW) contacts formed by layered BiTe are found effective in improving the performance of WSe pMOSFETs. As compared with conventional transition metal-based Ni/Au S/D contacts, over 10 times on-state current improvement is achieved. vdW interface formation between BiTe and WSe is confirmed by X-ray diffraction analysis and scanning transmission electron microscope observation. An atomically flat BiTe/WSe 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 BiTe are also effective in minimizing the impact of metal-induced gap states. These features offer WSe pMOSFETs with exceptional S/D junction characteristics, including suppressed off-state leakage and a higher on-off ratio. In addition, it is found that WSe pMOSFETs with BiTe 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.