Control over Nanoscale and Ultrafast Charge Transfer Using Terahertz Scanning Tunneling Microscopy

Terahertz scanning tunneling microscopy (THz-STM) has emerged as a powerful technique for probing ultrafast electron dynamics on nanometer scales. When combined with luminescence spectroscopy, THz-STM enables direct access to excited states and provides detailed insights into the dynamics of electron transfer at the tip–sample junction. In this review, we summarize basic mechanisms and recent advances in THz-STM-based investigations, highlighting their capabilities for visualizing transient phenomena in materials. We then examine how integrating THz-STM with luminescence spectroscopy enhances sensitivity to excited state dynamics and tunneling pathways. The demonstrated control over excited state formation via sequential electron tunneling offers new opportunities for ultrafast nanoscale spectroscopy and quantum state manipulation.