Deformation induced new pathways in silicon.

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• In situ nanomechanical testing on damaged brittle materials, like silicon (Si), has been lacking, obscuring deformation mechanisms.
• A gap exists between abrasive machining and current nanomechanical tests due to dissimilar nanostructures.
• Understanding Si deformation is crucial for advanced electronics and nanostructures.

Purpose of the Study:

• To perform in situ nanomechanical tests on damaged silicon using transmission electron microscopy (TEM).
• To investigate the deformation mechanisms and phase transitions in silicon under dynamic nanoindentation.
• To bridge the gap between abrasive machining and nanomechanical characterization of brittle materials.

Main Methods:

• Fabrication of an 80 nm thick silicon wedge.
• In situ dynamic nanoindentation within a transmission electron microscope (TEM) using a specialized cube corner indenter (66 nm tip radius).
• In situ atomic characterization and ab initio calculations to analyze deformation and phase transitions.

Main Results:

• Observed nanotwins, slip bands, and intersected stacking faults in silicon, bridging the machining-testing gap.
• Demonstrated a novel Si-I to Si-VI phase transition pathway induced by in situ TEM nanoindentation.
• Calculated a 1.21 eV increase in average potential energy and 2.444 nN average force per atom during the Si-I to Si-VI transition.

Conclusions:

• In situ TEM nanoindentation successfully characterized deformation mechanisms in damaged silicon.
• A new Si-I to Si-VI phase transition pathway was identified, offering fundamental insights.
• Findings provide crucial information for fabricating high-performance electronic devices and nanostructures.