79 research outputs found
New technology for metal nanorods formation
No full textThe ongoing research on a new technology suitable for the large-scale fabrication of arrays of metallic nanorods suitable as nanoantenna dipole electromagnetic collectors is presented. The actual diameter and the height of the nanorods, centered approximately at the middle of the visible spectrum, have been settled as D ∼25nm and H ∼250nm, respectively, in order to obtain a nanodipole antenna. The experimental work was carried on in two steps: first the synthesis of a template of anodic porous alumina by a two-step anodizing process of a 1100nm thick Al film, later the growing of the metallic nanorod inside the nanopores of the anodic template. It was used a new electroless metallic deposition method, based on a redox reaction of displacement realized by immersing the samples of nanoporous alumina into an acid solution made with cupric sulfate. Detailed scanning electron microscopy analysis of the samples structure is presented. SEM images show a copper nanorod with H = 35nm and D = 300nm
Immersion displacement deposition of copper on porous silicon for nanostructure fabrication
No full textFormation of composite nanostructures by corrosive deposition of copper into porous silicon
No full textIn this work we present a composite nanostructure based on PS-Cu and obtained by a corrosive deposition of Cu from an aqueous solution containing copper ions. PS samples of different porosities ranging from 15% to 75% were immersed in a 0.025 M CuSO4{dot operator}5H2O+0.005 M HF solution for different times. Scanning electron microscopy analysis was carried out to study the structural form of the PS-Cu nano-composite samples. It was clearly observed that Cu was deposited into and onto PS as nanosized granular film. Characteristic of Cu distribution, structural features of Cu film and factors that influence Cu film structure are described. It is shown that variation of PS porosity and corrosive deposition time provides formation of new composite PS-Cu structures. © 2007 Elsevier Ltd. All rights reserved
Copper displacement deposition on nanostructured porous silicon
No full textImmersion displacement technique innovated by introducing of hydrofluoric acid in solution for Cu deposition was used to decorate porous silicon with Cu. Porous silicon surface was found to be covered by Cu nanosized crystals. Simultaneously porous silicon skeleton was observed to dissolute during Cu solution immersion step. Principally different nanosized objects from porous silicon covered with separated or coalesced Cu nanoparticles to porous Cu membranes were formed. It was found variation of porous silicon preparation regimes allows creating both the rectifying and the ohmic Cu/porous silicon contacts. Crystallographic orientation of the initial Si and porous silicon porosity were revealed to strongly effect on conductivity of Cu films. Finally free standing porous silicon layer was converted into flexible porous Cu membrane by displacement method. Thickness of Cu membrane reached to 25 μm and its electrical conductivity was equal to 60-70% of bulk Cu
X-ray and electron backscattered diffractometry of copper nanoparticles grown on porous silicon
No full textElectrochemical Deposition and Characterization of Ni in Mesoporous Silicon
No full textNickel nanowires have been formed by stationary electrochemical deposition of nickel into mesoporous silicon templates from the modified Watts bath. Monitoring of the porous silicon potential during the electrochemical deposition has given the determination of the emergence of Ni on the outer surface of porous layer. Maximum filling factor of porous silicon with Ni has been achieved to 67%. The pore dimensions have been found to define the length and diameter of the Ni nanowires that have equaled to 10 mu m and 100-120 nm, respectively. The polycrystalline nature of the nickel nanowires, as well as the expansion of nickel lattice constant in comparison with bulk material has been established by analyzing the X-ray diffraction spectra. The synthesized samples have possessed ferromagnetic properties, which have been confirmed by temperature measurements of the magnetization. Smaller values of the specific magnetization of the Ni/PS samples and the atomic magnetic moment of Ni atoms at the low temperature with respect to those of bulk material have been suggested to be mostly caused by formation of nickel silicide at the beginning of the Ni electrochemical deposition. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.050210jes] All rights reserved
Electrochemical Deposition of Ni into Mesoporous Silicon
No full textNickel nanowires have been formed by the stationary electrochemical deposition of nickel into mesoporous silicon from the modified Watts bath. The polycrystalline nature of the Ni deposit has been established as well as expansion of its lattice parameter in comparison with bulk nickel. Control of the potential of porous silicon during electrochemical deposition allows to determine the moment of complete filling of pore space with Ni. The maximum achieved filling factor was 67% of the pores. The pore dimensions have been found to define the length and the diameter of the Ni nanowires that have equaled to 10 um and 100-120 nm, respectively. ©The Electrochemical Society
Comparative study of initial stages of copper immersion deposition on bulk and porous silicon
No full textInitial stages of Cu immersion deposition in the presence of hydrofluoric acid on bulk and porous silicon were studied. Cu was found to deposit both on bulk and porous silicon as a layer of nanoparticles which grew according to the Volmer-Weber mechanism. It was revealed that at the initial stages of immersion deposition, Cu nanoparticles consisted of crystals with a maximum size of 10 nm and inherited the orientation of the original silicon substrate. Deposited Cu nanoparticles were found to be partially oxidized to Cu2O while CuO was not detected for all samples. In contrast to porous silicon, the crystal orientation of the original silicon substrate significantly affected the sizes, density, and oxidation level of Cu nanoparticles deposited on bulk silicon
Porous silicon technology, a breakthrough for silicon photonics: From packaging to monolithic integration
No full textLow cost concept based on the porous silicon technology is shown to be well suitable for integrating monolithically the photonic devices on a standard silicon wafers by using localized SOI structures fabricated by electrochemical anodization of silicon wafers followed by thermal oxidation of porous silicon. The new approach consists in realizing buried localized porous oxidized silicon by exploiting two different routes: n- epi/n+/n- structures on p-type wafers and ionimplantation on standard CMOS/BiCMOS wafers. The peculiarities of the developed approach, including anodization and thermal oxidation regimes to form oxidized porous silicon regions with the required properties are presented. The advantages of the proposed approach in realizing the fiber-to-chip and power-over-fiber coupling are discussed. © 2014 IEEE
- …
