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 article, the electrical transport properties of SiO2 films (⩾3 μm in thickness) containing Ge nanocrystals have been studied and it was shown that the films exhibit T−1/2 dependence of ln(σ) under relatively low electric fields independent of the volume fraction of Ge in the films, where T and σ are the temperature and the conductivity, respectively.
Abstract: The electrical transport properties of SiO2 films (⩾3 μm in thickness) containing Ge nanocrystals have been studied We found that the films exhibit T−1/2 dependence of ln(σ) under relatively low electric fields independent of the volume fraction of Ge in the films, where T and σ are the temperature and the conductivity, respectively The observed electrical properties could be well explained by the theory developed by Simanek [Solid State Commun 40, 1021 (1981)] which considers the tunneling of thermally activated carriers between neighboring nanocrystals
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TL;DR: In this paper, the authors used the anharmonic-downward-distortion-following (ADD-Following) method to find the lowest barrier from the six-membered-ring structure in hexasilabenzene, and computed the barrier height to be only 74 kJ mol−1.
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Abstract: Luminescent silicon oxides containing radiative centers were obtained by using two different techniques. Silicon rich silicon oxides (SRSOs) were fabricated by rf magnetron sputter deposition and Ge-implanted SiO2 films were fabricated by ion implantation following the thermal oxidation of Si. Blue and violet photoluminescence were observed from the SRSO and the Ge-implanted SiO2, respectively. However, the electroluminescence (EL) spectra from both oxides exhibited red and near-infrared luminescence bands. Strong EL was observed only under reverse bias conditions on metal-luminescent oxide–semiconductor structures. The EL intensity and peak position were varied with applied voltages. According to the EL and current–voltage measurements, it is concluded that the possible EL mechanism is the impact ionization of ground state electrons in the radiative centers.
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TL;DR: Porous structured GaN nanowires were synthesized with a large scale by chemical vapor deposition of Ga/Ga 2 O 3 /B 2O 3 /C mixture under NH 3 flow as mentioned in this paper.
55 citations
TL;DR: In this article, the synthesis and characterization of nanocrystalline Si prepared by the initial reaction of the metal silicide, Mg 2 Si, with either SiCl 4 or Br 2 and, subsequently, with LiAlH 4.
Abstract: We describe the synthesis and characterization of nanocrystalline Si prepared by the initial reaction of the metal silicide, Mg 2 Si, with either SiCl 4 or Br 2 and, subsequently, with LiAlH 4 . These reactions produce Si nanoparticles with surfaces that are covalently terminated with H. The resultant nanoparticles can be suspended in organic solvent and are characterized by Fourier transform infrared (FTIR), UV–vis absorption, and photoluminescence (PL) spectroscopy. This work provides the first direct evidence of hydrogen terminated Si nanoparticles synthesized in solution.
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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