Electronic transport in planar atomic-scale structures measured by two-probe scanning tunneling spectroscopy

Area of Science:

• Surface Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Miniaturization of electronic circuits to the single-atom level necessitates advanced characterization techniques for transport properties.
• Scanning probe microscopy offers high precision for local characterization of atoms and molecules on surfaces.

Purpose of the Study:

• To investigate electronic transport along the anisotropic germanium (001) surface.
• To introduce and validate a method for determining transconductance in a two-probe scanning tunneling spectroscopy setup.

Main Methods:

• Utilized two-probe scanning tunneling spectroscopy (SPM).
• Performed first-principles transport calculations.
• Developed a transconductance determination method for energy-resolved surface state analysis.

Main Results:

• Observed two distinct resonances in transconductance spectroscopy, corresponding to the opening of two transport channels.
• Demonstrated anisotropic electron propagation along germanium dimer rows.
• Measured phase-coherence lengths up to 50 nm.

Conclusions:

• The developed transconductance method effectively characterizes energy-resolved electronic transport through unoccupied surface states.
• Findings confirm anisotropic electron propagation on the germanium (001) surface.
• This research provides a foundation for characterizing quantum circuits engineered at the surface level.