Mechanism of bistability causing streaky images with hydrogen-capped EAOGe-C2H imagers

Explain the mechanism behind the observed bistability that leads to streakiness in inverted-mode STM images produced by hydrogen-capped EAOGe-C2H molecules on H:Si(100)-2x1 SPC apexes, and determine the conditions under which this bistability occurs.

Background

During demonstrations of dangling bond patterning via mechanosynthetic hydrogen abstraction, the authors observe that hydrogen-capped imagers sometimes exhibit bistable behavior during scanning, manifesting as streaky images. This behavior is noted as not fully understood and presents a challenge for consistent characterization of reaction outcomes.

Resolving the origin and dynamics of this bistability—whether electronic, geometric, or related to molecule–surface interactions—would aid in achieving stable imaging and accurate identification of fabricated features.

References

In Figure S14c, there is a bistability, which we sometimes observe and do not fully understand, that leads to streakiness in the image.

— Inverted-Mode Scanning Tunneling Microscopy for Atomically Precise Fabrication  (2512.24431 - Barrera et al., 30 Dec 2025) in Supplementary Section 10 (Additional Data on Hydrogen Abstraction on H:SPC), Figure S14 discussion