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ABSTRACT: The authors demonstrates that doped epitaxial contacts to a Si nanowire improve R<sub>on</sub> and eliminate ambipolar conduction. Our n-FET mobility was shown to be comparable to standard n-channel Si mobility.
Device Research Conference, 2007 65th Annual; 07/2007
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ABSTRACT: The authors report the fabrication of a p -field effect transistor (FET) and an n -FET with a silicon nanowire channel and doped silicon source and drain regions. The silicon nanowires were synthesized by the vapor-liquid-solid method. For p -FETs the source and drain regions were formed by adding boron doped silicon to the unintentionally doped nanowire body at predefined locations using in situ doped silicon epitaxy. For n -FETs the epitaxial source and drain regions were grown undoped and were later implanted with P and As. The measured I<sub> d </sub>-V<sub> g </sub> characteristics of the devices exhibited unipolar transport, while reference FETs made with nanowires from the same batch but with Schottky (metal) contacts exhibited ambipolar characteristics.
Applied Physics Letters 07/2007; · 3.84 Impact Factor
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ABSTRACT: In-place bonding is a technique where silicon-on-insulator (SOI) slabs are bonded by hydrophobic attraction to the underlying silicon substrate when the buried oxide is undercut in dilute HF. The bonding between the exposed surfaces of the SOI slab and the substrate propagates simultaneously with the buried oxide etching. As a result, the slabs maintain their registration and are referred to as “bonded in-place”. We report the fabrication of dislocation-free strained silicon slabs from pseudomorphic trilayer Si/SiGe/SOI by in-place bonding. Removal of the buried oxide allows the compressively strained SiGe film to relax elastically and induce tensile strain in the top and bottom silicon films. The slabs remain bonded to the substrate by van der Waals forces when the wafer is dried. Subsequent annealing forms a covalent bond such that when the upper Si and the SiGe layer are removed, the bonded silicon slab remains strained.
Applied Physics Letters 06/2005; 86(25):251902-251902-3. · 3.84 Impact Factor
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ABSTRACT: We have investigated elastic strain relaxation, i.e., strain relaxation without the introduction of dislocations or other defects, in free-standing SiGe/Si structures. We fabricated free-standing Si layers supported at a single point by an SiO2 pedestal and subsequently grew an epitaxial SiGe layer. The measured strain relaxation of the SiGe layer agrees well with that calculated using a force-balance model for strain sharing between the SiGe and strained Si layers. We report strained Si layers with biaxial tensile strain equal to 0.007 and 0.012. © 2004 American Institute of Physics.
Applied Physics Letters 02/2004; 84(7):1093-1095. · 3.84 Impact Factor
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ABSTRACT: Blanket pseudomorphic Si0.8Ge0.2/Si layer structures grown by Rapid thermal Chemical Vapor Deposition (RTCVD) on SOI substrates were etched to form 5μm × 5μm slabs, supported by a single pedestal at the center. Symmetric tri-layer slabs, 20nm Si/236nm Si0.8Ge0.2/20nm Si supported by a SiO2 pedestal are flat and x-ray diffraction measurements of the strain and the thickness of the layers confirmed that the strain is shared between the Si and SiGe layers according to the ratio of the thickness of the SiGe and Si layers. These tri-layer structures were then firmly attached to the substrate using a filling material. A thermal oxide layer was grown on the upper and lower surface of the free-standing structures and then polycrystalline Si was deposited to fill the space between the free-standing structure and the Si substrate, thus attaching the bottom strained Si layer to the substrate. The polycrystalline Si was subsequently removed by reactive ion etching except from under the /SiGe/Si slab. The top SiO2 and Si layers as well as the SiGe layer were then removed selectively by wet etching. Raman spectroscopy measurements show that the strain in the attached strained Si-on-insulator layer is ε = 0.0067.
MRS Proceedings. 12/2003; 809.
