Mapping the ultrafast charge transfer in van der Waals heterostructures

摘要

We employ THz near-field microscopy to investigate ultrafast interlayer charge transfer in van der Waals heterostructures (HS) by tracing the resulting THz emission on the nanoscale. We further employ a novel concept of contact-free tunneling microscopy to monitor the interlayer electron-hole (e-h) pair population through its build up and decay, providing access to the ultrafast carrier dynamics with spatial resolution orders of magnitude better than the diffraction limit.