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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
TL;DR: In this article, self-assembled polymer spheres are used as masks for the deposition of hexagonal arrays of Ag islands on a silicon substrate, followed by the removal of the polymer spheres, the sample is etched with SF6 and CF4 at 100 W leading to hexagonal array of silicon nanopillars.
Abstract: We report the fabrication of ordered arrays of silicon nanopillars via reactive ion etching (RIE). Self-assembled polymer spheres are used as masks for the deposition of hexagonal arrays of Ag islands on a silicon substrate. Following the removal of the polymer spheres, the sample is etched with SF6 and CF4 at 100 W leading to hexagonal arrays of silicon nanopillars. The aspect ratio of the pillars can be influenced by the etching time; maximum aspect ratios of 15:1 have been produced.

49 citations

Journal ArticleDOI
TL;DR: In this paper, a process condition where well-dispersed Si nanocrystallites devoid of droplets and debris are prepared, by varying excitation laser conditions, was extracted, and the influence of the inert background gas pressures on transition from amorphous-like thin films to nanocrystites.
Abstract: Silicon (Si) nanocrystallites have been synthesized using pulsed-laser ablation in inert background gases, for studying the structures and optical properties as one of the quantum confinement effects. We extracted a process condition where well-dispersed Si nanocrystallites devoid of droplets and debris are prepared, by varying excitation laser conditions. Furthermore, we investigate the influence of the inert background gas pressures on transition from amorphous-like thin films to nanocrystallites. It was clarified that there is a processing window of the inert background gas pressure in which the quantum confinement effects for carriers and phonons become apparent.

49 citations

Journal ArticleDOI
TL;DR: In this article, the elastic strain of porous silicon membranes for potential use in the microsensor technology has been investigated by means of micro-Raman spectroscopy, where a depth distribution of the stress normal-to-the plane of formation has been measured with maximal stress value at the interface between the porous layer and the crystalline Si-substrate.

48 citations

Journal ArticleDOI
TL;DR: In this paper, the origin of 153μm emission from Er-doped xerogels fabricated onto micro-, meso-and macro-porous silicon is discussed and the application of sol-gel process for synthesis the 3D colloidal photonic crystals is discussed.

48 citations

Journal ArticleDOI
TL;DR: Starodub et al. as discussed by the authors used light emitting properties of porous silicon (PS) discovered earlier to create a bioaffinic sensor capable of detecting myoglobin in buffer solutions and human serum.
Abstract: Light emitting properties of porous silicon (PS) discovered earlier [L.T. Canham, Silicon quantum wire array fabrication by electrochemical dissociation of wafers, Appl. Phys. Lett. 57 (1990) 1046–1048] were used to create a bioaffinic sensor capable of detecting myoglobin in buffer solutions and human serum. For the fabrication of PS samples the scheme elaborated earlier [N.F. Starodub, L.L. Fedorenko, V.M. Starodub, S.P. Dikij, S.V. Svechnikov, Use of the silicon crystals photoluminescence to control immune complex formation, Sensors and Actuators B 35–36 (1996) 44–47] was used. It was shown that the sensitivity of the sensor created is 10 ng/ml. It is comparable with that of the standard ELISA method, but the overall time of the analysis performed by the sensor is much shorter. From the experiments in which operational stability was studied it can be concluded that the transducer can be used only for one cycle of measurements. PS immune sensor was successfully applied for the detection of the myoglobin level in human serum.

48 citations

References
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Journal ArticleDOI
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

Journal ArticleDOI
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

Journal ArticleDOI
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

Journal ArticleDOI
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