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Defect Characterization in SiGe/SOI Epitaxial Semiconductors by Positron Annihilation
R Ferragut1, A Calloni, A Dupasquier
1L-NESS, Dipartimento di Fisica, Politecnico di Milano, via Anzani 42, 22100 Como, Italy.
Nanoscale Research Letters
|December 21, 2010
Summary
Positron annihilation spectroscopy effectively characterizes atomic-scale defects in silicon-germanium (SiGe) thin films on ultra-thin body silicon-on-insulator. Annealing modifies defect structures, revealing germanium-rich trapping sites, likely Si vacancies near dislocations.
Area of Science:
- Materials Science
- Semiconductor Physics
- Nanotechnology
Background:
- Characterizing atomic-scale defects is crucial for semiconductor performance.
- Thin multilayer semiconductor structures present unique challenges for defect analysis.
- Positron annihilation spectroscopy (PAS) offers a non-destructive method for probing defects.
Purpose of the Study:
- To demonstrate the potential of PAS for atomic-scale defect characterization in SiGe/UTB-SOI.
- To analyze the defect profile and interface properties of SiGe thin films.
- To investigate the impact of post-growth annealing on defect structures.
Main Methods:
- Utilized a slow positron beam for depth-profiling defect analysis.
- Employed positron annihilation spectroscopy (PAS) for defect characterization.
- Performed chemical analysis to identify defect types and surrounding elements.
Main Results:
- Successfully characterized the SiO(2)/Si interface in ultra-thin body silicon-on-insulator (UTB-SOI), estimating its depth.
- Identified the interface as free of defects, containing only localized charged centers.
- Observed significant modifications in defect structure after vacuum annealing, indicating relaxation.
- Revealed prevalent trapping sites in SiGe layers rich in germanium, suggesting Si vacancies associated with dislocations.
Conclusions:
- PAS is a powerful technique for atomic-scale defect analysis in advanced semiconductor heterostructures.
- The SiO(2)/Si interface in UTB-SOI is robust, with defects primarily located within the SiGe layer.
- Post-growth annealing effectively modifies defect structures and can be used to study defect evolution in SiGe films.
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