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Journal ArticleDOI

Quantum size effects on the optical band gap of microcrystalline Si:H.

15 Sep 1988-Physical Review B (American Physical Society)-Vol. 38, Iss: 8, pp 5726-5729
TL;DR: The structural analysis showed that the materials consist of small crystalline silicon particles surrounded by hydrogen atoms, whose diameters are 20--30 A\r{}.
Abstract: We have succeeded in fabricating the mostly crystallized Si:H materials having a wide optical band gap of up to 2.4 eV by means of a reactive sputtering technique with a low substrate temperature of \ensuremath{\sim}100 K. The structural analysis showed that the materials consist of small crystalline silicon particles surrounded by hydrogen atoms, whose diameters are 20--30 A\r{}. The widening of the optical band gap can be explained by a three-dimensional quantum-well effect in the small particles.
Citations
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Journal ArticleDOI
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.

7,393 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that Si microcrystallites were embedded in a Si oxide matrix for the sample which emitted the light, and the inverse relation between emission energy and the square of the crystallite size indicates that carrier confinement in the Si micro-crystallite causes this photoluminescence phenomenon.
Abstract: Visible photoluminescence was observed in ultrafine Si particles at room temperature. Transmission electron microscopy revealed that Si microcrystallites were embedded in a Si oxide matrix for the sample which emitted the light. The emission energy depended on crystallite size in the range from 2.8 to 5 nm. The inverse relation between emission energy and the square of the crystallite size indicates that carrier confinement in the Si microcrystallites causes this photoluminescence phenomenon.

793 citations

Journal ArticleDOI
TL;DR: The BOLS correlation mechanism has been initiated and intensively verified as discussed by the authors, which has enabled the tunability of a variety of properties of a nanosolid to be universally reconciled to the effect of bond order deficiency of atoms at sites surrounding defects or near the surface edges of the nano-material.

775 citations


Additional excerpts

  • ...(a) The EPA blueshift of PS with data-1 [511], data-2 [513], data-3 [514], data-4 [515], and data-5 [45]....

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Journal ArticleDOI
TL;DR: In this paper, the authors compared the luminescence and vibrational properties of anodically oxidized (porous) silicon and of chemically synthesized siloxene (Si 6 O 3 H 6 ) and its derivates.

738 citations

Journal ArticleDOI
TL;DR: A new synthetic method was developed to produce robust, highly crystalline, organic-monolayer passivated silicon (Si) nanocrystals in a supercritical fluid by thermally degrading the Si precursor in the presence of octanol.
Abstract: A new synthetic method was developed to produce robust, highly crystalline, organic-monolayer passivated silicon (Si) nanocrystals in a supercritical fluid. By thermally degrading the Si precursor, diphenylsilane, in the presence of octanol at 500 °C and 345 bar, relatively size-monodisperse sterically stabilized Si nanocrystals ranging from 15 to 40 A in diameter could be obtained in significant quantities. Octanol binds to the Si nanocrystal surface through an alkoxide linkage and provides steric stabilization through the hydrocarbon chain. The absorbance and photoluminescence excitation (PLE) spectra of the nanocrystals exhibit a significant blue shift in optical properties from the bulk band gap energy of 1.2 eV due to quantum confinement effects. The stable Si clusters show efficient blue (15 A) or green (25−40 A) band-edge photoemission with luminescence quantum yields up to 23% at room temperature, and electronic structure characteristic of a predominantly indirect transition, despite the extremely...

465 citations