研究目的
To study the mechanical stress dependence of the Fermi level pinning at an oxidized silicon (001) surface using micro-Raman spectroscopy and micro-XPS mapping on statically deflected p-type silicon cantilevers.
研究成果
The Fermi level pinning at the oxidized silicon surface shows an even response to applied stress, with increases of 0.16 meV/MPa for compression and 0.11 meV/MPa for tension. This is attributed to the symmetry of Pb0 interface defects. The findings provide direct spectroscopic evidence for stress effects on surface electronic properties, relevant to nanoscale strained-silicon devices, and suggest the need for further theoretical studies.
研究不足
The study is limited to uniaxial stress along the ?110? direction and specific stress levels up to 240 MPa. Oxide thickness variations across the cantilever surface require corrections, and the method may not capture all interface defect behaviors. The interpretation relies on assumptions about Pb0 defects and their symmetry.
1：Experimental Design and Method Selection:
The study uses a combination of micro-Raman spectroscopy and micro-XPS mapping to investigate the stress dependence of Fermi level pinning. Cantilevers are deflected to apply uniaxial stress, and spectroscopic measurements are performed under ultra-high vacuum conditions.
2：Sample Selection and Data Sources:
p-type silicon cantilevers fabricated from silicon-on-insulator wafers with specific dimensions (length 11 mm, width 3 mm, device layer thickness 5 μm, buried oxide 1 μm, handle 400 μm thick). Samples are stored and prepared with photo-resist protection and cleaning.
3：List of Experimental Equipment and Materials:
Silicon cantilevers, diamond saw for dicing, photo-resist, acetone, iso-propyl alcohol, de-ionized water, sample mounts, actuator screw, micro-Raman spectroscopy system, XPS system (Scienta SES 2002 electron energy analyzer), TEMPO beamline at Soleil synchrotron.
4：Experimental Procedures and Operational Workflow:
Cantilevers are deflected using an actuator screw to apply compressive or tensile stress. Raman maps are acquired to measure stress distribution. XPS maps of Si 2p core levels are obtained with a focused X-ray beam. Data is correlated with stress from Raman maps and corrected for oxide thickness variations.
5：Data Analysis Methods:
Raman peak shifts are used to calculate stress. XPS spectra are fitted with Voigt functions to determine core level shifts. Stress-induced shifts in Fermi level pinning energy are analyzed, and band bending is estimated using bulk deformation potentials.
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