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Journal ArticleDOI

Silicon quantum wire array fabrication by electrochemical and chemical dissolution of wafers

03 Sep 1990-Applied Physics Letters (American Institute of Physics)-Vol. 57, Iss: 10, pp 1046-1048
TL;DR: In this paper, free standing Si quantum wires can be fabricated without the use of epitaxial deposition or lithography using electrochemical and chemical dissolution steps to define networks of isolated wires out of bulk wafers.
Abstract: Indirect evidence is presented that free‐standing Si quantum wires can be fabricated without the use of epitaxial deposition or lithography. The novel approach uses electrochemical and chemical dissolution steps to define networks of isolated wires out of bulk wafers. Mesoporous Si layers of high porosity exhibit visible (red) photoluminescence at room temperature, observable with the naked eye under <1 mW unfocused (<0.1 W cm−2) green or blue laser line excitation. This is attributed to dramatic two‐dimensional quantum size effects which can produce emission far above the band gap of bulk crystalline Si.
Citations
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Journal ArticleDOI
16 Feb 1996-Science
TL;DR: In this article, the authors focus on the properties of quantum dots and their ability to join the dots into complex assemblies creates many opportunities for scientific discovery, such as the ability of joining the dots to complex assemblies.
Abstract: Current research into semiconductor clusters is focused on the properties of quantum dots-fragments of semiconductor consisting of hundreds to many thousands of atoms-with the bulk bonding geometry and with surface states eliminated by enclosure in a material that has a larger band gap. Quantum dots exhibit strongly size-dependent optical and electrical properties. The ability to join the dots into complex assemblies creates many opportunities for scientific discovery.

10,737 citations

Journal ArticleDOI
TL;DR: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency as mentioned in this paper, and many DSC research groups have been established around the world.
Abstract: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

8,707 citations


Cites background from "Silicon quantum wire array fabricat..."

  • ...The striking optical properties of nanoporous silicon obtained by photoanodic etching [54] extended the materials research scope of photoelectrochemistry to other porous crystalline semiconductors [55]....

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Journal ArticleDOI
TL;DR: In this article, the authors present methods of severe plastic deformation and formation of nanostructures, including Torsion straining under high pressure, ECA pressing, and multiple forging.

5,763 citations

Journal ArticleDOI
22 Jan 1999-Science
TL;DR: The synthesis of massive arrays of monodispersed carbon nanotubes that are self-oriented on patterned porous silicon and plain silicon substrates is reported and the mechanisms of nanotube growth and self-orientation are elucidated.
Abstract: The synthesis of massive arrays of monodispersed carbon nanotubes that are self-oriented on patterned porous silicon and plain silicon substrates is reported. The approach involves chemical vapor deposition, catalytic particle size control by substrate design, nanotube positioning by patterning, and nanotube self-assembly for orientation. The mechanisms of nanotube growth and self-orientation are elucidated. The well-ordered nanotubes can be used as electron field emission arrays. Scaling up of the synthesis process should be entirely compatible with the existing semiconductor processes, and should allow the development of nanotube devices integrated into silicon technology.

3,093 citations

Journal ArticleDOI
TL;DR: A large amount of work world wide has been directed towards obtaining an understanding of the fundamental characteristics of porous Si as mentioned in this paper, and the key importance of crystalline Si nanostructures in determining the behaviour of porous si is highlighted.
Abstract: A large amount of work world-wide has been directed towards obtaining an understanding of the fundamental characteristics of porous Si. Much progress has been made following the demonstration in 1990 that highly porous material could emit very efficient visible photoluminescence at room temperature. Since that time, all features of the structural, optical and electronic properties of the material have been subjected to in-depth scrutiny. It is the purpose of the present review to survey the work which has been carried out and to detail the level of understanding which has been attained. The key importance of crystalline Si nanostructures in determining the behaviour of porous Si is highlighted. The fabrication of solid-state electroluminescent devices is a prominent goal of many studies and the impressive progress in this area is described.

2,371 citations

References
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Journal ArticleDOI
TL;DR: In this article, an irradiated carbon-rich silicon diode with an internal quantum efficiency more than 103 times higher than that of band-to-band recombination in an unirradiated, but otherwise identical diode was reported.
Abstract: We report 77‐K electroluminescence from an irradiated carbon‐rich silicon diode that has an internal quantum efficiency more than 103 times higher than that of band‐to‐band recombination in an unirradiated, but otherwise identical diode. This is achieved by creating optically active Cs‐SiI‐Cs complexes with room‐temperature electron bombardment at an energy between the displacement thresholds for single vacancy and divacancy formation. Under these irradiation conditions, it is possible to create a high concentration of radiative defects without gross degradation of the diode’s electrical characteristics. The technique could provide very large scale integration‐compatible silicon light‐emitting diodes for 1.3–1.6 μm all‐silicon integrated optics.

74 citations

Book ChapterDOI
J. R. Haynes1
TL;DR: In this paper, the authors examined both at room temperature and at 77 °K and found that the photon energies associated with the maximum photon emission of intrinsic and extrinsic radiation are in semi-quantitative agreement with accepted values of ionization energies of the donor and acceptor impurities introduced in the crystal growing process.
Abstract: Radiation produced in silicon by the recombination of excess electrons and holes in thermal equilibrium with the crystal lattice has been examined both at room temperature and at 77 °K The radiation obtained at room temperature is shown to be an intrinsic property of silicon It is probably due to indirect transitions of electrons from the conduction band minima to the valence band with phonon cooperation Additional radiation is found at 77 °K which is structure sensitive, or extrinsic This radiation is shown to be produced by the recombination of excess carriers with unionized donor and acceptor impurities The energy distribution of the photons of intrinsic radiation gives values of the energy gap which are in good agreement with those determined in other ways Differences between the photon energies associated with the maximum photon emission of intrinsic and extrinsic radiation are in semi-quantitative accord with accepted values of ionization energies of the donor and acceptor impurities introduced in the crystal growing process

71 citations

Journal ArticleDOI
TL;DR: In this article, the electroluminescence of silicon was investigated in the temperature range between 300 and 77 °K, and an absolute measurement of the internal quantum efficiency yields a room temperature value of 2 × 10−6 for the band-to-band emission.
Abstract: The electroluminescence of silicon was investigated in the temperature range between 300 and 77 °K. The near edge emission is due to indirect band-to-band transitions associated with TO and TA phonon emission/absorption. The intensity-voltage relation shows that this emission is connected with the diffusion current. At low voltages, additional long wavelength emission is observed which is connected with recombination in the space charge region. An absolute measurement of the internal quantum efficiency yields a room temperature value of 2 × 10−6 for the band-to-band emission. This value is well described by a theoretical radiative lifetime derived from van Roosbroeck-Shockley statistics and by an experimental non-radiative lifetime. Die Elektrolumineszenz von Silizium p-n Ubergangen wurde zwischen 300 und 77 °K untersucht. Die Emission nahe der Bandkante wird durch indirekte Band-Band-Ubergange unterstutzt durch TO- und TA-Phononen gedeutet. Diese Strahlungskomponente ist mit dem Diffusionsstrom gekoppelt, wie die Intensitat-Spannungs-Abhangigkeit zeigt. Bei kleinen Spannungen wird eine langwellige Emission, die mit Rekombination in der Raumladungszone gekoppelt ist, beobachtet. Eine Absolutmessung der inneren Quantenausbeute ergibt den Wert 2 × 10−6 fur 300 °K. Er kann theoretisch bei Kenntnis einer nichtstrahlenden Lebensdauer durch eine Berechnung der strahlenden Lebensdauer nach van Roosbroeck-Shockley bestimmt werden.

49 citations

Journal ArticleDOI
TL;DR: In this paper, optical and structural properties of low-defect-density a-SiHx alloys are reported. But the properties of these alloys were not discussed.
Abstract: We report on optical and structural properties of a new class of efficient visible light emitting semiconductors: low-defect-density a-SiHx alloys. Films are prepared by HOMOCVD from silane and RF plasma from disilane. Optical gaps increase monotonically with H incorporation and decreasing substrate temperatures (200-25°C), while spin densities remain low. New broadband luminescence develops in the alloy band tails and shifts to higher energies with the gap. At ∼ 40% H, gaps reach 2.55 eV and yellow-orange PL peaks near 2.05 eV. Efficient PL persists at room temperature. Emission is attributed to band-tail excitons and phonon cooperation.

48 citations