| 1. |
- Bhaskar, U., et al.
(författare)
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On-chip tensile testing of the mechanical and electro-mechanical properties of nano-scale silicon free-standing beams
- 2011
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Ingår i: Advanced Materials Research. - 1662-8985 .- 1022-6680. ; 276, s. 117-126
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Tidskriftsartikel (refereegranskat)abstract
- A simple and versatile on-chip tensile testing method is proposed for the statistical evaluation of size effects on the mechanical strength of silicon thin films along with the simultaneous study of (from low to ultra) strain effects on the carrier transport. Mechanical results are presented on the fracture strength of micro-nano scale silicon beams, followed with a discussion on interface states and problems facing reliable nano-electronic and nano-electromechanical characterizations
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| 2. |
- Kalem, S., et al.
(författare)
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Black silicon with high density and high aspect ratio nanowhiskers
- 2011
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Ingår i: Nanotechnology. - : IOP Publishing. - 1361-6528 .- 0957-4484. ; 22:23
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Tidskriftsartikel (refereegranskat)abstract
- The physical properties of black silicon (b-Si) formed on Si wafers by reactive ion etching in chlorine plasma are reported in an attempt to clarify the formation mechanism and the origin of the observed optical and electrical phenomena, which are promising for a variety of applications. The b-Si consisting of high density and high aspect ratio sub-micron length whiskers or pillars with tip diameters of well under 3 nm exhibits strong photoluminescence (PL) both in the visible and the infrared, which is interpreted in conjunction with defects, confinement effects and near band-edge emission. Structural analysis indicates that the whiskers are all crystalline and encapsulated by a thin Si oxide layer. The infrared vibrational spectrum of Si-O-Si bondings in terms of transverse-optic (TO) and longitudinal-optic (LO) phonons indicates that disorder induced LO-TO optical mode coupling can be an effective tool in assessing the structural quality of the b-Si. The same phonons are likely coupled to electrons in visible region PL transitions. Field emission properties of these nanoscopic features are demonstrated indicating the influence of the tip shape on the emission. Overall properties are discussed in terms of the surface morphology of the nanowhiskers.
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| 3. |
- Kalem, S., et al.
(författare)
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Controlled thinning and surface smoothening of silicon nanopillars
- 2011
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Ingår i: Nanotechnology. - : IOP Publishing. - 1361-6528 .- 0957-4484. ; 20:44, s. 445303-
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Tidskriftsartikel (refereegranskat)abstract
- A convenient method has been developed to thin electron beam fabricated silicon nanopillars under controlled surface manipulation by transforming the surface of the pillars to an oxide shell layer followed by the growth of sacrificial ammonium silicon fluoride coating. The results show the formation of an oxide shell and a silicon core without significantly changing the original length and shape of the pillars. The oxide shell layer thickness can be controlled from a few nanometers up to a few hundred nanometers. While downsizing in diameter, smooth Si pillar surfaces of less than 10 nm roughness within 2 µm were produced after exposure to vapors of HF and HNO3 mixture as evidenced by transmission electron microscopy (TEM) analysis. The attempt to expose for long durations leads to the growth of a thick oxide whose strain effect on pillars can be assessed by coupled LO–TO vibrational modes of Si–O bonds. Photoluminescence (PL) of the pillar structures which have been downsized exhibits visible and infrared emissions, which are attributable to microscopic pillars and to the confinement of excited carriers in the Si core, respectively. The formation of smooth core–shell structures while reducing the diameter of the Si pillars has a potential in fabricating nanoscale electronic devices and functional components.
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| 4. |
- Kalem, S., et al.
(författare)
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Microscopic Si whiskers
- 2011
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317. ; 88:8, s. 2593-2596
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Tidskriftsartikel (refereegranskat)abstract
- Physical properties of microscopic silicon whiskers formed by reactive ion etching in chlorine plasma are reported in an attempt to clarify the formation mechanism and the origin of the observed optical and electrical phenomena. The silicon whiskers with diameters of well under 5 nm exhibit strong photoluminescence (PL) both in visible and infrared, which are related to quantum confinement, near band-edge and defects. Vibrational analysis indicate that disorder induced LO-TO optical mode coupling is very effective. Electric field emission properties of these microscopic features were also investigated to determine their potential for advanced technology applications. (C) 2011 Elsevier B.V. All rights reserved.
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| 5. |
- Passi, V., et al.
(författare)
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Anisotropic vapor HF etching of silicon dioxide for Si microstructure release
- 2012
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317. ; 95, s. 83-89
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Tidskriftsartikel (refereegranskat)abstract
- Damages are created in a sacrificial layer of silicon-dioxide by ion implantation to enhance the etch rate of silicon-dioxide in liquid and vapor phase hydrofluoric acid. The etch rate ratio between implanted and unimplanted silicon-dioxide is more than 150 in vapor hydrofluoric acid (VHF). This feature is of interest to greatly reduce the underetch of microelectromechanical systems anchors. Based on the experimentally extracted etch rate of unimplanted and implanted silicon-dioxide, the patterning of the sacrificial layer can be predicted by simulation.
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| 6. |
- Passi, V., et al.
(författare)
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High-Throughput On-Chip Large Deformation of Silicon Nanoribbons and Nanowires
- 2012
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Ingår i: Journal of Microelectromechanical Systems. - 1057-7157. ; 21:4, s. 822-829
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Tidskriftsartikel (refereegranskat)abstract
- An on-chip internal stress-based testing device has been developed in order to deform silicon nanoribbons and nanowires up to large strains enabling high throughput of data. The fracture strain and survival probability distribution have been generated for 50-nm-thick and 50- or 500-nm-wide specimens with lengths varying between 2.5 and 10 mu m. Fracture strains reaching up to 5% are attained in the smallest specimens, whereas 90% of the specimens survive 2.5% deformation. This testing platform opens an avenue to investigate and use electromechanical couplings appearing under large mechanical stress or large deformation.
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| 7. |
- Passi, V., et al.
(författare)
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Note: Fast and reliable fracture strain extraction technique applied to silicon at nanometer scale
- 2011
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 82:11, s. art. no 116106-
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Tidskriftsartikel (refereegranskat)abstract
- Simple fabrication process and extraction procedure to determine the fracture strain of monocrystalline silicon are demonstrated. Nanowires/nanoribbons in silicon are fabricated and subjected to uniaxial tensile stress along the complete length of the beams. Large strains up to 5% are measured for nanowires presenting a cross section of 50 nm × 50 nm and a length of 2.5 μm. An increase in fracture strain for silicon nanowires (NWs) with the downscaling of their volume is observed, highlighting the reduction of the defects probability as volume is decreased.
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| 8. |
- Velessiotis, D., et al.
(författare)
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Molecular junctions made of tungsten-polyoxometalate self-assembled monolayers: Towards polyoxometalate-based molecular electronics devices
- 2011
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317. ; 88:8, s. 2775-2777
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the electrical conduction of planar Au junctions electrically bridged by a polyoxometalate-based self-assembled monolayer, aimed to be used in hybrid silicon/molecular memory devices, is discussed. Tunnelling assisted by the presence of polyoxometalate anions is recognised as the main conduction mechanism for these devices. Fluctuations and hysteresis that are profoundly observed in the current-voltage characteristics for the smallest junctions suggest that the anions number is the more crucial factor in the devices behaviour. Quantitative analysis of the obtained characteristics based on Simmons's model reveals an increase in the tunnelling barrier height as the electrode distance increases from 20 to 200 nm. (C) 2011 Elsevier B.V. All rights reserved.
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| 9. |
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| 10. |
- Bengtsson, Stefan, 1961, et al.
(författare)
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Silicon on aluminum nitride structures formed by wafer bonding
- 1994
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Ingår i: 1994 IEEE International SOI Conference Proceedings. ; , s. 35-
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with the use of reactively sputtered aluminum nitride (AlN) films as insulators for Bond and Etch-back Silicon-On-Insulator (BESOI) materials. In SOI-applications where high power is dissipated in the silicon SOI-film the low thermal conductivity of the buried silicon dioxide layer may cause a temperature rise in the silicon film detrimentally affecting the device performance. An attractive alternative would be to replace the silicon dioxide of the SOI structure with another material, like diamond, silicon carbide or aluminum nitride. The thermal conductivity of AlN is considerably larger than that of Si02. This paper presents results on how sputter deposition of AlN may be combined with wafer bonding for the creation of highly thermally conductive SOI structures
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