Two-dimensional Gaussian fitting for precise measurement of lattice constant deviation from a selected-area...

Area of Science:

• Materials Science
• Nanotechnology
• Electron Microscopy

Background:

• Traditional strain mapping methods like X-ray diffraction and Raman spectroscopy have limited spatial resolution.
• Convergent-beam electron diffraction (CBED) and nanobeam electron diffraction (NBED) offer high precision but are limited to beam-insensitive samples.
• Selected-area electron diffraction (SAED) is suitable for various samples but traditionally lacks spatial resolution and precision.

Purpose of the Study:

• To develop an improved SAED technique for precise strain mapping at the nanoscale.
• To overcome the limitations of spatial resolution and precision in existing SAED methods.
• To provide a competitive alternative for nanoscale strain analysis.

Main Methods:

• Utilized a two-dimensional stage-scanning system to acquire diffraction patterns at multiple sample positions.
• Employed fixed beam conditions throughout the data acquisition process.
• Applied iterative nonlinear least-squares fitting for precise measurement of spot displacement in each diffraction pattern.

Main Results:

• Achieved strain measurement precision comparable to CBED and NBED techniques.
• Demonstrated the capability to precisely determine strain at nanoscale dimensions.
• The developed method offers high spatial resolution and precision in strain mapping.

Conclusions:

• The enhanced nanosized SAED technique provides a simple yet precise method for nanoscale strain mapping.
• This technique is competitive with existing methods like CBED and NBED, especially for beam-sensitive materials.
• Offers a valuable tool for characterizing strain in nanomaterials and devices.