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Dual-Beam Sample Preparation

Materials characterization is an essential strength of the focused-ion beam (FIB) platform. Material can be removed or added while observing the evolution of the surface topography features of the specimen with ion beam stimulated secondary electrons

NREL's dual-beam focused-ion beam workstation for fabricating microscopy samples and nanostructures.

The dual-beam focused-ion-beam (FIB) workstation consists of a FIB column and a scanning electron microscope (SEM) column on the same platform. Uses include ion milling, metal deposition, ion imaging, and electron imaging on the micrometer and nanometer scale of advanced photovoltaic materials and devices.

The dual-beam FIB supports other analytical tools such as Transmission Electron Microscopy (TEM), and precise, site-specific sample preparation (example) for TEM, SEM, and local electrode atom probe (LEAP) (example).

Acquiring chemical spectra and elemental maps is another feature of this system with energy-dispersive spectroscopy (EDS) (example). Three-dimensional chemical reconstructions can be obtained by combining controlled ion milling with chemical mapping. The FIB is equipped with a gas injection system (GIS) platinum metal deposition capability that can be used with either ion-beam-assisted or electron-beam-assisted chemical vapor deposition (example). Using a digital patterning generator also allows for complete FIB milling or deposition of complex structures with software-supplied parameters or by direct input of bitmap files (or both).

Examples of Dual-Beam Focused-Ion-Beam Sample Fabrication Capabilities

SEM microphoto of contacts attached to a nanowire. FIB: chemical vapor deposition — SEM image taken in the dual beam FIB showing nano deposition with GIS of Pt contacts to a single GaN nanowire.
Set of three TEM images showing cutting of trenches to remove a wafer section and transferring that section to a grid post. Set of three TEM images showing cutting of trenches to remove a wafer section and transferring that section to a grid post.
FIB: TEM sample preparation — FIB prepared TEM cross-section (from A to C) Opposing trenches are milled out with the Ga+ ion source and a 1-2 µm thin section is left free standing in the wafer. A side view shows the depth of the trenches. The section is then welded to the micro-manipulator, extracted from the wafer then transferred and welded to a TEM grid post. Final thinning down to a thickness of < 100nm is achieved using low incident angles and low Ga ion current. Set of three TEM images showing cutting of trenches to remove a wafer section and transferring that section to a grid post.
SEM image of sharpened probe sample tip. FIB: LEAP sample preparation — SEM image taken in the dual beam FIB showing sharpened LEAP sample tip prepared by Ga+ ion milling in the FIB.
FIB: EDS elemental mapping — EDS elemental maps taken in the dual beam FIB showing In, Ga, P, and As distributions in cross-section of a III-V compound semiconductor multi-junction solar cell. Scanning electron image of cross-section of a multijunction solar cell followed by EDS elemental maps of the indium, gallium, phosphorus, and arsenic in the cross-section.
Scanning electron image of cross-section of a multijunction solar cell followed by EDS elemental maps of the indium, gallium, phosphorus, and arsenic in the cross-section. Scanning electron image of cross-section of a multijunction solar cell followed by EDS elemental maps of the indium, gallium, phosphorus, and arsenic in the cross-section.
Scanning electron image of cross-section of a multijunction solar cell followed by EDS elemental maps of the indium, gallium, phosphorus, and arsenic in the cross-section. Scanning electron image of cross-section of a multijunction solar cell followed by EDS elemental maps of the indium, gallium, phosphorus, and arsenic in the cross-section.

For further information, contact Mowafak Al-Jassim, 303-384-6602.