Silicon quantum wire array fabrication by electrochemical and chemical dissolution of wafers
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.
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TL;DR: In this paper, a new approach of porous silicon (PS) formation using a vapour-etching (VE)-based technique is presented, which shows clear evidence of the formation of a porous layer when Si substrates are submitted to VE.
84 citations
Patent•
09 Oct 1992TL;DR: In this article, a method for producing a semiconductor article comprises the steps of preparing a first substrate having a non-porous semiconductor layer on a porous semiconductor region, forming unevenness on the surface at the side of said semiconductor layers of said first substrate; bonding the surface of the first substrate with said unevenness formed thereon to the surface surface of a second substrate so as to be in contact with each other, and removing said porous semiconductors under the state that said semiconductes layer is bonded to said second substrate to thereby transfer the semiconductor
Abstract: A method for producing a semiconductor article comprises the steps of preparing a first substrate having a non-porous semiconductor layer on a porous semiconductor region, forming unevenness on the surface at the side of said semiconductor layer of said first substrate; bonding the surface of said first substrate having said unevenness formed thereon to the surface of said second substrate so as to be in contact with each other, and removing said porous semiconductor under the state that said semiconductor layer is bonded to said second substrate to thereby transfer said semiconductor layer from said first substrate onto said second substrate.
84 citations
TL;DR: The overall strategy of using T-DMA for monitoring monolayer uptake could be generally applied to study surface processing of other aerosolized nanoparticle systems.
Abstract: A new method is described for surface functionalization of silicon nanocrystals. Organic monolayers were self-assembled via gas-phase adsorption of amines, alkenes, alkynes, and aldehydes onto the surfaces of aerosolized crystalline silicon nanoparticles of 12.2 nm diameter in an atmospheric pressure tube reactor. Assembly took place within 4 s at temperatures between 200 and 500 °C. The extent of adsorption was measured by using tandem differential mobility analysis (T-DMA), an on-line diagnostic method for measuring changes in particle size. Functionalized particles were further characterized by high-resolution transmission electron microscopy and diffuse reflectance Fourier transform infrared spectroscopy. The apparatus described in this work can be used for continuous mass production of functionalized silicon nanoparticles. Moreover, the overall strategy of using T-DMA for monitoring monolayer uptake could be generally applied to study surface processing of other aerosolized nanoparticle systems.
84 citations
TL;DR: In this article, random porous silicon dielectric multilayers are proposed as interesting materials for applications as optical components, where the randomness is obtained as a variation in the layer thicknesses.
Abstract: Random porous silicon dielectric multilayers are proposed as interesting materials for applications as optical components. Distributed Bragg reflectors and interferential Fabry - Perot filters are demonstrated. The randomness is obtained as a variation in the layer thicknesses. The advantage in the use of random instead of periodic multilayers lies in the obtention of a wider stop-band in Bragg reflectors with the same difference in the refractive indexes of the layers and in a higher finesse in Fabry - Perot filters.
84 citations
TL;DR: The photoluminescent properties of porous silicon nanostructures have received intense study since 1990 as discussed by the authors and a literature review focuses on the large number of models proposed to account for efficient light emission.
Abstract: The striking photoluminescent properties of porous silicon nanostructures have received intense study since 1990. This literature review focuses on the large number of models proposed to account for efficient light emission. Two distinct luminescence bands in the visible spectral range have received most study. Strong evidence now exists that quantum confined carriers in crystalline Si can yield efficient red to green ('S band') luminescence. The blue ('F band') emission reported to date in oxidised porous Si is, however, unlikely to arise from quantum confinement effects.
83 citations
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TL;DR: In this article, the properties of electrolyte-semiconductor barriers are described, with emphasis on germanium, and the use of these barriers in localizing electrolytic etching is discussed.
Abstract: Properties of electrolyte-semiconductor barriers are described, with emphasis on germanium. The use of these barriers in localizing electrolytic etching is discussed. Other localization techniques are mentioned. Electrolytes for etching germanium and silicon are given.
1,039 citations
TL;DR: It is found that a standard, widespread, chemical-preparation method for silicon, oxidation followed by an HF etch, results in a surface which from an electronic point of view is remarkably inactive, which has implications for the ultimate efficiency of silicon solar cells.
Abstract: We have found that a standard, widespread, chemical-preparation method for silicon, oxidation followed by an HF etch, results in a surface which from an electronic point of view is remarkably inactive. With preparation in this manner, the surface-recombination velocity on Si111g is only 0.25 cm/sec, which is the lowest value ever reported for any semiconductor. Multiple-internal-reflection infrared spectroscopy shows that the surface appears to be covered by covalent Si-H bonds, leaving virtually no surface dangling bonds to act as recombinatiuon centers. These results have implications for the ultimate efficiency of silicon solar cells.
910 citations
TL;DR: In this paper, multiple internal infrared reflection spectroscopy has been used to identify the chemical nature of chemically oxidized and subsequently HF stripped silicon surfaces, and these very inert surfaces are found to be almost completely covered by atomic hydrogen.
Abstract: Multiple internal infrared reflection spectroscopy has been used to identify the chemical nature of chemically oxidized and subsequently HF stripped silicon surfaces. These very inert surfaces are found to be almost completely covered by atomic hydrogen. Results using polarized radiation on both flat and stepped Si(111) and Si(100) surfaces reveal the presence of many chemisorption sites (hydrides) that indicate that the surfaces are microscopically rough, although locally ordered. In particular, the HF‐prepared Si(100) surface appears to have little in common with the smooth H‐saturated Si(100) surface prepared in ultrahigh vacuum.
588 citations
TL;DR: In this article, the authors measured hydrogen desorption from monohydride and dihydride species on crystalline-silicon surfaces using transmission Fourier-transform infrared (FTIR) spectroscopy.
Abstract: Hydrogen desorption kinetics from monohydride and dihydride species on crystalline-silicon surfaces were measured using transmission Fourier-transform infrared (FTIR) spectroscopy. The FTIR desorption measurements were performed in situ in an ultrahigh-vacuum chamber using high-surface-area porous-silicon samples. The kinetics for hydrogen desorption from the monohydride and dihydride species was monitored using the SiH stretch mode at 2102 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ and the ${\mathrm{SiH}}_{2}$ scissors mode at 910 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$, respectively. Annealing studies revealed that hydrogen from the ${\mathrm{SiH}}_{2}$ species desorbed between 640 and 700 K, whereas hydrogen from the SiH species desorbed between 720 and 800 K. Isothermal studies revealed second-order hydrogen desorption kinetics for both the monohydride and dihydride surface species. Desorption activation barriers of 65 kcal/mol (2.82 eV) and 43 kcal/mol (1.86 eV) were measured for the monohydride and dihydride species, respectively. These desorption activation barriers yield upper limits of 84.6 kcal/mol (3.67 eV) and 73.6 kcal/mol (3.19 eV) for the Si-H chemical bond energies of the SiH and ${\mathrm{SiH}}_{2}$ surface species.
479 citations