R. Herino

University Joseph Fourier - Grenoble 1, Grenoble, Rhône-Alpes, France

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Publications (65)97.81 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 01/2010; 26(5).
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    ABSTRACT: This paper presents preliminary results on the selective growth of three-dimensional (3D) micrometric metallic structures by the MOCVD technique. The D structure growth occurs by simply feeding the reactor gas phase with a conventional flow of metal-organic (MO), trimethyl-gallium (TMGa) molecules. Selectivity occurs at the substrate surface in which MO species travel tens of micrometers in order to build up the 3D structure. After the growth, these structures are nitrided in order to give GaN-related optical visible emission. Optical emission results are presented and discussed in this paper. Both 3D structures deposition and annealing experiments can be extended to other III–V materials.
    Journal of Crystal Growth 01/2004; 272(1):466-474. · 1.55 Impact Factor
  • B. Gelloz, A. Bsiesy, R. Herino
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    ABSTRACT: Electrically induced photoluminescence (PL) quenching from reverse-biased p+-type porous silicon (PS) and forward biased oxidized n-type PS, as well as their dynamics, have been investigated. The two systems exhibit common properties. The energy selectivity of the PL quenching by the applied potential is much lower than with nonoxidized n-type PS. The PL quenching time is independent of the emission energy. It is governed by carrier injection into PS and is limited by the Helmoltz capacitance at the electrolyte–PS interface and the electrolyte resistivity. The PL recovery time is longer than the quenching time and increases as the emission energy decreases. It is limited by the transparency of the energy barrier (due to oxide in the case of oxidized n-type PS and the depletion region in the case of p+-type PS) at the PS–substrate interface. It is shown that electron storage into PS is possible for time in excess of several seconds depending on parameters such as the oxidation level, the PS thickness, and the electrolyte resistivity. © 2003 American Institute of Physics.
    Journal of Applied Physics 08/2003; 94(4):2381-2389. · 2.21 Impact Factor
  • H. Diesinger, A. Bsiesy, R. Hérino
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    ABSTRACT: A new experimental set-up has been developed which uses the environment of near field optical microscopy to locally induce photo-electrochemical reactions at a semiconductor surface in contact with an electrolyte. When the semiconductor is under reverse bias, illumination of the surface by the optical tip of the microscope creates photogenerated carriers which are separated by the electric field in the space charge region. The charge carriers which are driven to the surface can react with the surface atoms or with electro-active species diluted into the electrolyte. Depending on the electrolyte composition and owing to the polarization conditions, one can induce selected photo-electrochemical reactions which may result in the etching of the surface or in the deposition of different materials at the nanometer scale. Several examples of applications are given: the photo-current mapping of silicon surfaces patterned with porous silicon, the localized photo-induced etching of silicon at the submicron scale, and the nanostructuring of porous silicon by direct writing.
    physica status solidi (a) 05/2003; 197(2):561 - 565. · 1.21 Impact Factor
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    ABSTRACT: Anodic oxidation of porous silicon, the inner surface of which is covered by a thin layer of Ge, has been studied. The Ge layer is first oxidized during a time proportional to the amount of Ge, prior to oxidation of the porous silicon. It is shown how anodic oxidation can be used as a new method for the measurement of the amount of Ge incorporated into porous silicon pores. It is also a valuable technique for evaluating the homogeneity of the Ge coverage.
    physica status solidi (a) 01/2003; 197(1):123-127. · 1.21 Impact Factor
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    ABSTRACT: A technique allowing near-field photocurrent (PC) mapping of silicon surfaces in contact with an electrolyte is presented. The illumination source is an optical fibre tip with a 100-nm aperture. A shear force detection system controls the tip-sample distance while scanning the tip across the silicon-electrolyte interface. Topographic and PC images on SiO2/Si mesas both show 300 nm resolution. It is shown that this PC contrast is induced by the tip-topography interaction and hence the PC resolution is limited by the resolution of the topography. Indeed, PC mapping on topography-less patterned porous-silicon/silicon samples shows that the lateral resolution is only limited by the aperture size which is of the order of 100 nm.
    Journal of Microscopy 05/2001; 202(Pt 1):223-8. · 1.63 Impact Factor
  • H. Diesinger, A. Bsiesy, R. Hérino
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    ABSTRACT: The application of a near-field optical device to the electrochemical deposition of submicron nickel dots on silicon is demonstrated. The silicon-electrolyte junction behaves like a Schottky diode where the electrolyte plays the role of the metal. The junction is reverse biased so that only a negligible dark current is flowing across the junction. The optical tip of the near-field device is used as a local lightsource to control a photocurrent on a submicron scale, which allows one to create submicron objects of nickel by locally triggering the electrochemical reduction of nickel ions. The effect of the lateral diffusion of the photogenerated carriers on the form of the deposited nickel dots is described by a two-dimensional carrier diffusion model.
    Journal of Applied Physics 01/2001; 90:4862-4864. · 2.21 Impact Factor
  • Journal of Applied Physics 01/2001; 89:5801-5801. · 2.21 Impact Factor
  • Heinrich Diesinger, Ahmad Bsiesy, Roland Hérino
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    ABSTRACT: Detailed experimental procedure of an in situ photoelectrical technique applied to porous silicon absorption coefficient measurement is described. In this technique, the underlying silicon substrate is used as a photodetector of the monochromatic light intensity transmitted by the porous layer. In particular, the investigation of spectral range validity of this technique has evidenced that at high photon energy, the porous silicon photoluminescence (PL) is excited and contributes to the photocurrent. It is shown that this PL contribution can be readily separated from that of the directly transmitted light, providing two benefits: first, the high accuracy of the measurement remains unaffected by the PL at high excitation energy, which justifies the application to photon energy as high as 3 eV, and second, the PL component can be further exploited to measure the porous silicon PL quantum efficiency. Typical absorption coefficient spectra obtained by this technique are then recalled. They are discussed in the frame of a model based on the analysis of the absorption coefficient of an ensemble of different quantum-size silicon crystallites. © 2001 American Institute of Physics.
    Journal of Applied Physics 12/2000; 89(1):221-225. · 2.21 Impact Factor
  • L Montès, R Hérino
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    ABSTRACT: The incorporation of ZnSe into luminescent porous silicon layers (PSL) by electrochemical co-deposition of Zn and Se is described by focusing on the critical parameters related to the specific nature of porous silicon. The PSL photoluminescence is monitored during the growth of ZnSe to reveal the effects of the process on the optical properties of the structure, allowing an in-situ characterization of the growth. The structure and chemical composition of the resulting nanostructures are investigated by transmission electron microscopy (TEM) and chemical microanalysis which show homogeneous incorporation of ZnSe inside the porous matrix with no segregation. Crystallization of ZnSe by subsequent thermal annealing is also studied and preliminary characterizations of the electrical properties of the resulting nanocomposite structures are presented.
    Materials Science and Engineering B 01/2000; 69:136-141. · 1.85 Impact Factor
  • L. Montès, F. Muller, R. Hérino
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    ABSTRACT: Electroplating of II-VI semiconductors like ZnSe into porous silicon can be an efficient and low cost method to fill the porous volume with a transparent and conductive material. With n-type porous layers, ZnSe impregnation is more effective near the sample surface because of reaction rate limitations due to diffusion in the electrolyte. In this paper, it is shown that the deposition of ZnSe into p-type porous silicon can be localized in the lower part of the porous layer if the reduction reaction rate is monitored by limiting the charge carrier supply. This can be done by controlling the power of the laser beam which photo-generates the carriers at the bottom of the pores. Studying the porous layer chemical composition by Auger electron spectroscopy confirms that the deposit is localized at the pore bottom, whereas the changes in the chemical composition of the porous silicon surface are analyzed by infra-red spectroscopy.
    Journal of Porous Materials 01/2000; 7(1):77-80. · 1.35 Impact Factor
  • Source
    Roland Hérino
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    ABSTRACT: The open porous structure and the very large specific surface area of porous silicon have motivated scientists to introduce different materials into the pores, forming composite structures devoted to different applications relying on the luminescence properties or the sensing capability of the resulting nanostructures. In this paper, the various composite structures that have been formed from porous silicon layers in recent years are reviewed, by focusing on the different methods used for deposition: dry processes, impregnation by contact with a liquid, chemical bath deposition or electrochemical deposition. Special attention is given to the particular requirements and specific drawbacks of each process.
    Materials Science and Engineering B 01/2000; · 1.85 Impact Factor
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    ABSTRACT: A new in-situ technique allowing accurate measurements of the porous silicon optical absorption coefficient α is described. This technique is based on the measurement of the photocurrent generated in the substrate under light excitation through the porous layer, and does not require to dry the porous layer or to detach it from the silicon substrate. The absorption spectra of p-type and p+-type porous layers have been measured from 1.5 to 3 eV for a wide range of porosities. The results are analysed by focusing on the possible effect of quantum confinement. It is concluded that confinement does not account for the α dependence upon porosity over the full investigated range, but that it is only responsible for the faster decrease of α towards the absorption edge that is observed for highly porous and luminescent layers. An absorption model is developed that takes into account the effect of the quantum confinement on the density of states of the silicon nanocrystallites and that complies with the observed spectral behavior.
    Materials Science and Engineering B 01/2000; 69:167-170. · 1.85 Impact Factor
  • B Gelloz, A Bsiesy, R Herino
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    ABSTRACT: The photoluminescence quenching of lightly doped p-type porous silicon in contact with aqueous acidic electrolytes is investigated under reverse-bias conditions. A complete and reversible quenching of the light emission is observed under infra-red illumination of the samples. This quenching is assigned to the injection into the porous layer of the electrons which are photogenerated in the substrate. The quenching features are studied as a function of the electron concentration in the porous layer, which is varied either by changing the intensity of the light excitation that generates the minority carriers in the silicon bulk or, at a given light intensity, by changing the electrolyte composition. In the latter case, the electron concentration is dependent on the electrochemical reactions which take place at the porous layer surface and which partly consume the injected electrons. It is shown that the amount of injected electrons directly determines the magnitude of the quenching and the associated spectral changes. It is concluded that the assumption of an enhanced charge carrier separation by the electric field as a possible quenching mechanism can be ruled out, and that the experimental results rather support the hypothesis that the quenching involves an Auger recombination process.
    Journal of Luminescence 09/1999; · 2.14 Impact Factor
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    ABSTRACT: Most physical deposition methods are unable to cover the inner surface of porous silicon (PS), whereas electroplating has been successfully used. So it seems very attractive to use the electrochemical deposition of a semiconductor such as CdTe to create a nanocomposite structure and to provide charge injection into the structure. We show that CdTe can be deposited on silicon and porous silicon from an electrolyte containing CdSO4 and TeO2 in acidic conditions. Physical analysis by X-ray diffraction, X-ray photoelectron spectroscopy and Auger electron spectroscopy confirm that the deposits are microcrystalline CdTe showing a preferential orientation along the (111) direction. After deposition, the photoluminescence intensity of porous silicon is found to be strongly affected, particularly upon drying. © 1997 Elsevier Science S.A.
    Thin Solid Films 01/1997; · 1.87 Impact Factor
  • Solid State Phenomena. 01/1997; 54:119-126.
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    ABSTRACT: This work is devoted to the analysis of the voltage dependence of the luminescence of n-type nanoporous films. The correlations between the behaviour of the photoluminescence and electroluminescence signal obtained from the same sample allow one to confirm that the emission quenching mechanism is related to the injection of electrons into the crystallites. When the samples are partially oxidised, the injection conditions are strongly modified, leading to significant changes in the observed voltage dependence of the emission.
    Thin Solid Films 01/1996; 276(1):130-133. · 1.87 Impact Factor
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    ABSTRACT: The remarkable voltage-tunable electroluminescence (VTEL) observed on porous silicon—electrolyte junctions is investigated in relation to material morphology and electrolysis parameters. The electroluminescence (EL) is obtained upon cathodic polarization of n-type porous silicon in contact with aqueous solutions containing the persulphate ion. The observed long-lived EL shows a reversible spectral shift as large as 300 nm for an external bias variation of about 0.6 V. The study of the EL behaviour as a function of the external voltage and the persulphate ion concentration shows that while the amplitude of the EL is proportional to the intensity of the exchanged current, the spectral position is only determined by the applied voltage. A qualitative model, taking into account the voltage dependence of the charge injection probability into the size-distributed silicon crystallites, gives a good description of the observed VTEL behaviour.In a similar manner, cathodic polarization induces a dramatic change in the porous silicon photoluminescence. It leads to a reversible, highly contrasted and energy-selective quenching of the photoluminescence (QPL) for a polarization variation of only about 500 mV. A spectral blue shift, along with a significant narrowing of the PL line accompanies the observed strong QPL. This results from selective quenching starting at the low luminescence energy and reaching progressively the high luminescence energy as the cathodic polarization is increased. Just as for VTEL, this selective character of the QPL can be explained by a voltage-induced enhancement of charge injection into the size-distributed silicon nanocrystallites.
    Thin Solid Films 01/1995; 255(1):80-86. · 1.87 Impact Factor
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    ABSTRACT: Porous silicon luminescence can be strongly modified by the application of an external bias (energy-selective quenching of the photoluminescence, reversible voltage tuning of the cathodic electroluminescence), as the result of selective carrier injection into the silicon nanocrystallites of the porous layer. Partial oxidation of the material is shown to strongly modify this selectivity and the voltage dependence of the light emission by changing the voltage drop distribution in the material.
    Microelectronic Engineering - MICROELECTRON ENG. 01/1995; 28(1):233-236.
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    ABSTRACT: The voltage‐tunable electroluminescence (VTEL) observed on porous silicon‐electrolyte system is investigated in relation with the material photoluminescence (PL). It is shown that the PL line is the envelope of all the emitted EL spectra obtained upon the bias variation. Consequently, a blueshift of the (PL) line leads to a similar shift of all the corresponding EL lines. This strongly suggests a common origin of these two phenomenon. Moreover, this study seems to indicate that the VTEL of porous silicon is related to the size and efficiency distributions of the silicon nanocrystallites associated with an electrically induced selective carrier injection. © 1994 American Institute of Physics.
    Applied Physics Letters 01/1995; · 3.79 Impact Factor