Publications
142 results found
Li CB, Fobelets K, Stevens V, et al., 2010, Study of Ag-assisited two-stage electroless etched Si nanowire array, Int. Symp. Atom-scale Si Hybrid Nanotech. "More-than-Moore and beyond"
Durrani ZAK, 2010, Single-electron devices and circuits in silicon, London, Publisher: Imperial College Press, ISBN: 978-1-84816-413-0
This book reviews research on single-electron devices and circuits in silicon. These devices provide a means to control electronic charge at the one-electron level and are promising systems for the development of few-electron, nanoscale electronic circuits. The book considers the design, fabrication, and characterization of single-electron transistors, single-electron memories, few electron transfer devices such as electron pumps and turnstiles, and single-electron logic devices. A review of the many different approaches used for the experimental realisation of these devices is provided and devices developed during the author’s own research are used as detailed examples. An introduction to the physics of single-electron charging effects is included.
Rafiq MA, Masubuchi K, Durrani ZAK, et al., 2009, Single electron charging effects in silicon nanochains, Int. Conf. on Solid State Devices and Materials
Rafiq MA, Durrani ZAK, Mizuta H, et al., 2009, Effective temperature conduction in silicon nanocrystals, IEEE Int. Conf. on Nano/Micro Engineered and Molecular Systems
Durrani ZAK, Rafiq MA, 2009, Electron transport in silicon nanocrystals and nanochains, Microelectronic Engineering, Vol: 86, Pages: 456-466
Si nanocrystals and nanochains, prepared by material synthesis, provide a means to define nanoscale devices using growth rather than lithographic techniques. Electronic transport in thin films of Si nanocrystals is influenced strongly by single-electron charging and quantum-confinement effects, and by the grain boundary regions between nanocrystals. This paper reviews electronic transport mechanisms in Si nanocrystal materials. These include thermionic emission of electrons across grain boundaries, space charge limited current, hopping transport, and single-electron charging effects. The fabrication of single electron devices in Si nanocrystal thin films and nanochains is considered, particularly with regards to their operation at room temperature.
Durrani ZAK, 2008, Electron conduction and charging effects in silicon nanocrystals, 2nd Int. Workshop on Semiconducting Nanoparticles
Ding PW, Fobelets K, Durrani ZAK, 2008, Electrical transport in polymer covered Si Nanowires, Micro- and Nano-Engineering Conf., Athens (2008)
Rafiq MA, Durrani ZAK, Mizuta H, et al., 2008, Silicon nanochains: Electron transport properties and applications, Int. Conf. on Physics of Semiconductors
Rafiq MA, Durrani ZAK, Mizuta H, et al., 2008, Single electron transport simulations in silicon nanochains, Condensed Matter and Materials Physics
Rafiq MA, Durrani ZAK, Mizuta H, et al., 2008, Room temperature single electron charging in single silicon nanochains, Journal of Applied Physics, Vol: 103, Pages: 053705-053705-4
Single-electron charging effects are observed at room temperature in single Si nanochains. Thenanochains, grown by thermal evaporation of SiO solid sources, consist of a series of Sinanocrystals 10 nm in diameter, separated by SiO2 regions. Multiple step Coulomb staircasecurrent-voltage characteristics are observed at 300 K in devices using single, selected, nanochains. The characteristics are investigated using a model where the nanochain forms a multiple tunnel junction. The single-electron charging energy for a nanocrystal within the multiple-tunnel junction is EC=e^2 /2Ceff ˜0.32 eV, 12kBT at 300 K
Rafiq MA, Durrani ZAK, Mizuta H, et al., 2008, Field dependant hopping conduction across silicon nanocrystal films, Journal of Applied Physics, Vol: 104, Pages: 123710-123710-3
We investigate the electric field dependence of hopping conduction in 300 nm thick films of ˜8 nmdiameter silicon nanocrystals. The hopping conductivity σ follows a lnσ proportional to 1/T^1/2 dependence with temperature T, explained by a percolation hopping conduction model. At high fields F ˜ 10^5 V/cm, the hopping conductivity follows a lnσ proportional to F^1/2 dependence. This dependence is investigated using the concept of “effective temperature,” introduced originally by Shklovskii for hopping conduction in disordered materials.
Yamahata G, Tsuchiya Y, Oda S, et al., 2008, Control of Electrostatic Coupling Observed for Silicon Double Quantum Dot Structures, Japanese Journal of Applied Physics, Vol: 47, Pages: 4820-4826
We study the electrostatic coupling in the silicon double quantum dot (DQD) structure as a key building block for a charge-based quantum computer and a quantum cellular automaton (QCA). We realize the three interdot coupling regimes of the DQD structure only by optimizing the DQD design and the thermal oxidation condition. We then demonstrate that the electrostatic coupling between DQDs can be modulated by tuning the negative voltage of the side gate electrode. Note that the interdot coupling was largely modulated with a small decrease in the gate voltage from 0 to -100 mV because our structure initially has the DQD geometry. Furthermore, the device fabrication is compatible with the conventional silicon complementary metal–oxide–semiconductor (CMOS) process. This structure is suitable for the future integration of CMOS devices. In addition, we show the derivation of the DQDs' capacitances, including the gate cross capacitances, as a function of the spacing between the two adjacent charge triple points. By using these capacitances, the electron transport properties of the DQD structure are simulated, and the modulation of the electrostatic coupling is successfully simulated as the change of the total capacitance in DQDs
Rafiq MA, Mizuta H, Uno S, et al., 2007, Fabrication of vertical nanopillar devices, Microelectronics Engineering, Vol: 84, Pages: 1515-1518
Electron transport in silicon nanopillars has been investigated, with a view to developing vertical electron emission, electroluminescentand photoluminescent devices. Arrays of nanopillars were fabricated in highly-doped single crystal silicon and polysilcon materials. A ‘natural lithography’ technique utilising colloidal gold particles as an etch mask, in conjunction with standard microfabriction techniques, was used to fabricate the nanopillars in selected regions. The pillar height was 100 nm in single crystal silicon material and 40 nm in polysilicon material and the diameter of the pillars was 30 nm. A top contact was supported on a polyimide film, deposited by spin coating and curing, and then etching-back in oxygen plasma to expose the pillar tops. The current–voltage characteristics of these devices were measured at range of temperatures.
Durrani ZAK, Ahmed H, 2007, Nanosilicon single-electron transistors and memory, Nanosilicon, Editors: Kumar, London, Publisher: Elsevier Press, ISBN: 978-0-08-044528-1
Nanosilicon materials are promising systems for the fabrication of single-electron transistor and memory devices in silicon. In these devices, precise control over the charging of a nanometre-size ‘island’ by just one electron raises the possibility of low power, highly scaled integrated circuits with one electron per bit. Nanosilicon materials, consisting of crystalline silicon grains ~10 nm in size, provide a means to fabricate ultra-small charging islands using growth techniques rather than high-resolution lithography. It is then possible to fabricate single-electron devices operating at room temperature. This review introduces electron transport in nanosilicon and considers the design and fabrication of single-electron transistors, quantum-dot transistors, and few-electron memory cells in these materials
Servati P, Colli A, Hofmann S, et al., 2007, Scalable silicon nanowire photodetectors, Physica E, Vol: 38, Pages: 64-66
This paper presents photodetectors having vertically stacked electrodes with sub-micron (300 nm) separation based on silicon nanowire (SiNW) nanocomposites. The thin-film-like devices are made using standard photolithography instead of electron beam lithography and thus are amenable to scalable low-cost manufacturing. The processing technique is not limited to SiNWs and can be extended to different nanowires (NWs) (e.g., ZnO, CdSe) and substrates. The current–voltage characteristics show Schottky behaviourthat is dependent on the properties of the contact metal and that of the pristine SiNWs. This makes these devices suitable for examinationof electronic transport in SiNWs. Preliminary results for light sensitivity show promising photoresponse that is a function of effectiveNW density.
Rafiq M A, Tsuchiya Y, Mizuta H, et al., 2006, Hopping conduction in size-controlled Si nanocrystals, Journal of Applied Physics, Vol: 100, Pages: 014303-1-014303-4, ISSN: 0021-8979
Khalafalla, M A H, Mizuta H, et al., 2006, Observation of interdot coupling phenomena in nanocrystalline silicon point-contact structures, Current Appl. Phys, Vol: 6
Rafiq M A, Mizuta H, Uno S, et al., 2006, Fabrication of vertical nanopillar devices
Khalafalla, M A H, Mizuta H, et al., 2006, Identifying single-electron charging islands in a two-dimensional network of nanocrystalline silicon grains using Coulomb oscillation fingerprints, Phys. Rev. B, Vol: 74, Pages: 035316-1-035316-7, ISSN: 1098-0121
Khalafalla, M A H, Mizuta H, et al., 2005, Variation of Electrostatic Coupling and Investigation of Current Percolation Paths in Nanocrystalline Silicon Cross Transistors
Durrani Z, Rafiq M A, Colli A, et al., 2005, Catalyst-free Silicon Nanowires and Nanocrystals: Growth and Electron Transport
Rafiq M A, Tsuchiya Y, Mizuta H, et al., 2005, Temperature dependence of space charge limited current (SCLC) in thin films of silicon nanocrystals
Rafiq M A, Tsuchiya Y, Mizuta H, et al., 2005, Charge injection and trapping in silicon nanocrystals, Applied Physics Letters, Vol: 87
Khalafalla, M A H, Durrani Z, et al., 2005, Inter-grain coupling effects on Coulomb oscillations in dual-gated nanocrystalline silicon point-contact transistors, Thin Solid Films, Vol: 487
He J, Durrani Z, Ahmed H, 2004, Two-way switch for binary decision diagram logic using silicon single-electron transistors, Microelectronics Engineering, Vol: 73-74
Mizuta H, Furuta Y, Kamiya T, et al., 2004, Nanosilicon for single-electron devices, Current Appl. Phys., Vol: 4
Khalafalla, M A H, Mizuta H, et al., 2004, Electron coupling states in quantum dots in nanocrystalline silicon
Durrani Z, Kamiya T, Mizuta H, 2004, Electron Transport in Nanocrystalline Silicon, Recent Research Developments in Applied Physics (Vol. 7, Transworld Research Network
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