Time-Resolved Mapping of Charge Carrier Dynamics and Defect-Mediated Migration Barriers in TiO₂

The spatiotemporal behavior of charge carriers in metal oxides governs their performance in photocatalytic and electronic applications, yet remains poorly understood at the nanoscale. Here, we use time-resolved atomic force microscopy (TR-AFM) to map charge transport in TiO₂under controlled surface irradiation and thermal conditions. Our measurements reveal pronounced spatial variability in carrier migration times and activation energies, driven by local defect landscapes. Irradiation-induced surface defects are found to lower migration barriers, enhancing carrier relaxation. Notably, we observe electrostatic memory effects, with residual electric fields modulating migration dynamics across hundreds of nanometers. Temperature-dependent studies further reveal a tunable interaction between defect-mediated migration and thermal activation. These findings provide direct insight into nanoscale charge transport in TiO₂and highlight the role of defect engineering and thermal management in optimizing oxide-based devices for energy conversion and sensing.