Combination of high spatial resolution and low minimum detection limit using thinned specimens in cutting-edge...

Area of Science:

• Materials Science
• Analytical Chemistry
• Geochemistry

Background:

• Field-emission electron probe microanalysis with wavelength dispersive X-ray spectroscopy (FE-EPMA-WDX) is a powerful analytical technique.
• Optimizing sample preparation is crucial for enhancing the performance of microanalysis techniques.
• Understanding the impact of sample thickness is key to improving spatial resolution and minimum detection limits (MDL).

Purpose of the Study:

• To investigate the effect of sample thickness on spatial resolution and MDL in FE-EPMA-WDX.
• To compare the performance of thin-sample FE-EPMA-WDX with traditional bulk-sample analysis.
• To determine the optimal sample thickness for achieving high-resolution and low MDL analyses.

Main Methods:

• Indium gallium phosphide (InGaP) samples were prepared at various thicknesses (100, 130, 210, 310, and 430 nm).
• FE-EPMA-WDX analysis was performed on both thinned and bulk samples.
• The spatial resolution and MDL were systematically measured for each sample thickness.

Main Results:

• Thin-sample FE-EPMA-WDX achieved spatial resolutions ranging from 40-350 nm and MDLs from 13,000-600 ppm.
• Thin-sample analysis demonstrated superior sensitivity and spatial resolution compared to bulk samples.
• Analysis of chlorine (Cl) in silicon dioxide (SiO2) showed a spatial resolution of 41 nm and an MDL of 446 ppm for thin samples, outperforming bulk samples (348 nm resolution, 426 ppm MDL).

Conclusions:

• Sample thickness is a critical parameter that can be tuned to optimize spatial resolution and MDL in FE-EPMA-WDX.
• Thin-sample FE-EPMA-WDX offers significant advantages in sensitivity and spatial resolution over bulk-sample analysis.
• The findings enable more precise elemental analysis of materials at the nanoscale.