Quantum-trajectory Monte Carlo method for study of electron-crystal interaction in STEM

Area of Science:

• Materials Science
• Quantum Mechanics
• Computational Physics

Background:

• Electron microscopy and spectroscopy are crucial for materials analysis.
• Achieving atomic resolution in secondary electron imaging presents significant challenges.
• Understanding electron scattering mechanisms is vital for advanced imaging techniques.

Purpose of the Study:

• To develop a novel simulation method for electron beam-solid interactions.
• To elucidate the mechanism behind atomic resolution secondary electron imaging.
• To investigate electron scattering and secondary electron generation in crystalline solids.

Main Methods:

• Developed a quantum-trajectory Monte Carlo simulation method.
• Combined Bohmian quantum trajectories for elastic scattering with Monte Carlo for inelastic scattering.
• Utilized time-dependent Schrödinger equation and multislice method for wave function calculation.
• Simulated secondary electron generation, transport, and emission.

Main Results:

• The simulation method accurately models electron elastic and inelastic scattering.
• Inner-shell ionization events are identified as the primary source of high-energy secondary electrons.
• Simulated images for Si(110) crystals show good agreement with experimental data.
• The study confirms inner-shell ionization as the dominant mechanism for atomic resolution secondary electron imaging.

Conclusions:

• The developed quantum-trajectory Monte Carlo method is effective for studying electron beam-solid interactions.
• Inner-shell ionization events are critical for achieving atomic resolution in secondary electron microscopy.
• This work provides fundamental insights into imaging mechanisms in advanced electron microscopy.