Huaiyu Zhang

Huaiyu Zhang

Affiliation: Chinese Academy of Sciences

Research Interests: Scanning Prob e Microscope (S P M), THz Ultrafast Spectrum and Techniques, Quantum Sensing, Magnetometry

Title: Development of a Cryogen-Free THz-STM and Characterization of THz-Gundlach Oscillation

Abstract: Terahertz-Scanning Tunneling Microscope (THz-STM) integrating THz pulses and STM for simultaneous high spatio-temperal resolution, is pivotal for studying surface dynamics at atomic scale in real space. We developed a novel THz-STM system employing off-chamber parabolic mirror focusing and remote liquefaction-based continuous-flow cryogen-free cooler. Upon introducing the single-cycle THz pulses generated via the tilted wavefront method, significant THz-driven current signals were observed on a variety of samples with both sub-picosecond time resolution and atomic-scale spatial resolution. Using this THz-STM system, we systematically studied the THz-Gundlach oscillations on Si surface. We identified transient ring-shaped and THz-phase-dependent anomalies of THz-driven current. These findings reveal long-term carrier relaxation processes on semiconductor surfaces and provide new insights into the generation mechanisms of THz-driven current.