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Large-area plan-view sample preparation for GaAs-based systems grown by molecular beam epitaxy
D J Howard1, D C Paine, R N Sacks
1Division of Engineering, Brown University, Providence, Rhode Island 02912.
Journal of Electron Microscopy Technique
|June 1, 1991
Summary
A new chemical lift-off method for plan-view transmission electron microscopy (TEM) sample preparation enables large-area, constant-thickness analysis of GaAs-based epitaxial films, enhancing crystal quality evaluation.
Area of Science:
- Materials Science
- Solid State Physics
- Nanotechnology
Background:
- Transmission electron microscopy (TEM) is crucial for evaluating crystal quality in semiconductor epitaxial systems.
- Existing TEM sample preparation methods can be limiting for large-area analysis of complex structures.
Purpose of the Study:
- To develop a novel, chemically-based plan-view TEM sample preparation technique.
- To enable large-area, high-quality TEM analysis of GaAs/InxGa1-xAs/GaAs strained-layer films.
Main Methods:
- Utilizing extreme etch-rate selectivity between GaAs and AlAs in hydrofluoric acid/water solutions.
- Employing a 10 nm AlAs release layer for chemical lift-off of the layered structure.
- Mounting the lifted-off films on copper TEM grids for analysis.
Main Results:
- Achieved TEM transparent areas of up to 1 x 2 mm with a constant thickness of 196.4 nm.
- Successfully prepared plan-view TEM samples of GaAs/InxGa1-xAs/GaAs strained-layer films.
- Demonstrated the effectiveness of the chemical lift-off technique for crystal quality evaluation.
Conclusions:
- This simple, large-area plan-view TEM sample preparation method significantly enhances the evaluation of crystal quality in GaAs-based epitaxial systems.
- The technique relies solely on chemical methods, making it accessible and efficient.
- It extends the utility of TEM for detailed structural analysis of semiconductor heterostructures.