Mapping Concurrent Charge Carrier Dynamics at Semiconductor Surfaces Using Frequency-Domain Surface Photovoltage...

Area of Science:

• Surface science
• Semiconductor physics
• Spectroscopy

Background:

• Understanding charge carrier dynamics at semiconductor surfaces is crucial for device performance.
• Current methods lack the spatial and temporal resolution to fully characterize complex dynamics.

Purpose of the Study:

• To introduce a novel technique, frequency-domain inversion for surface photovoltage microscopy (FI-SPVM), for quantitative analysis of surface charge carrier dynamics.
• To achieve high spatial and temporal resolution for mapping concurrent carrier pathways.

Main Methods:

• Combines Kelvin probe force microscopy with periodic illumination and lock-in detection.
• Employs a linear time-invariant system model with convex inversion, sparsity, and total variation regularization.
• Analyzes surface photovoltage spectra across a wide frequency range.

Main Results:

• Resolves signed distributions of charge carrier relaxation times from nanoseconds to seconds.
• Successfully disentangles overlapping carrier pathways and identifies their lifetimes and polarities.
• Generates spatially resolved maps linking nanoscale structures to specific carrier dynamics.

Conclusions:

• FI-SPVM provides a robust framework for mapping concurrent charge carrier dynamics with nanoscale resolution.
• The technique is validated on synthetic and experimental data, demonstrating accuracy and practical applicability.
• Offers broad potential for studying complex semiconductor systems like photocatalysts and perovskite photovoltaics.