E. Gheeraert

Institut Néel, Grenoble, Rhône-Alpes, France

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Publications (133)204.97 Total impact

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    ABSTRACT: One the main key point to overcome for the development of a diamond metal-oxide-semiconductor field effect transistor (MOS-FET) relies on the gate oxide, in particular in the control of the band alignment, band curvature and of the interface traps at the diamond/oxide interface. Atomic layer deposition (ALD) of high-κ dielectrics seems to be the most suitable deposition technique to control the diamond/oxide interface as it was recently reported in the literature [1,2]. The authors reported the study of ALD-Al 2 O 3 and ALD-HfO 2 on hydrogenated(H)-diamond for the application in MOS-FET device [3]. The present work focuses on the electrical characteristics of Oxygen(O)-terminated boron doped diamond MOS capacitors initiated by the work of Chicot et al. [4]. The gate contacts were composed of Ti/Pt/Au metals on top of different ALD oxides deposited at 473 K. A Savannah 100 ALD system was used to deposit HfO 2 , ZrO 2 and Al 2 O 3 films on O-terminated boron doped diamond. The thicknesses were 25 nm for the ALD-HfO 2 and ALD-Al 2 O 3 films and 30 nm for the ALD-ZrO 2 film.
    Hasselt Diamond workshop 2014, SBDD XIX, Hasselt, Belgium; 02/2014
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    ABSTRACT: High forward current density of 103 A/cm2 (at 6 V) and a breakdown field larger than 7.7 MV/cm for diamond diodes with a pseudo-vertical architecture, are demonstrated. The power figure of merit is above 244 MW/cm2 and the relative standard deviation of the reverse current density over 83 diodes is 10% with a mean value of 10−9 A/cm2. These results are obtained with zirconium as Schottky contacts on the oxygenated (100) oriented surface of a stack comprising an optimized lightly boron doped diamond layer on a heavily boron doped one, epitaxially grown on a Ib substrate. The origin of such performances are discussed.
    Applied Physics Letters 02/2014; 104:052105-052105-4. · 3.79 Impact Factor
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    ABSTRACT: In the view of predicting the performances as well as anticipating the architecture of the future diamond devices, it is of fundamental importance to accurately implement the physical properties of diamond into finite element based softwares. In this context, we used Silvaco to model a diamond p-n junction and studied the carrier densities responsible for the electrical characteristics of the devices. The simulated electrical characteristics are compared to experimental data and the influence of Shockley-Read-Hall and Auger recombination models on the carrier densities and J(V) characteristics were investigated. The bias voltage boundary between low and high injection condition, Ψbi= 4.7 eV, was well reproduced. However, the extremely low calculated carrier densities lead to extremely low current densities in the low injection regime, reaching the numerical precision limit. The simulation of the reverse characteristic predicts a breakdown voltage of 225 V. Preliminary results on hopping conductivity implementation into the simulation tool are presented. Eventually, these results will be used to predict the architecture and behavior of future devices, such as bipolar junction transistor and metal-oxyde-semiconductor field effect transistor.
    Diamond and Related Materials. 01/2014;
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    ABSTRACT: Phone: þ30 2810 394 132, Fax: þ30 2810 394 106 Vapor–liquid–solid (V–L–S) growth of SiC on (100) diamond substrate is reported. The crystalline quality is evaluated by transmission electron microscopy (TEM). Diffraction contrast (CTEM) observations allowed confirm-ing the growth of fully lattice relaxed SiC 3C-type crystalline structure. Defects as dislocations at the diamond/SiC interface and stacking faults, in the thick SiC layer are revealed by high resolution TEM and CTEM. From the invisibility criteria, using dark field observations, <110> type Burger vector are identified. ß 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Silicon carbide is a widely investiga-ted material due to its physical properties such as its wide bandgap, high temperature stability, and high breakdown electric field. In addition, SiC is mature for some device architectures, thus commercial high power devices have been developed, outperforming Si-based counterparts. On the other hand, diamond exhibits superior characteristics, but the characteristics of diamond related semiconducting devices are still far from promising potentialities of diamond. Among them, fabricating good electrical contacts to diamond, with low resistance, good adherence, and high reliability is still difficult [1]. Therefore, the combined use of both materials can be an interesting approach, in particular for power electric devices. Up to now, for high power applications, diamond and SiC have been competitive materials. However, since SiC is inert with respect to diamond, growing SiC-related device structures on diamond can join the advantage of maturity to other diamond-related characteristics. In particular, it can be an alternative to improve local technological problems as ohmic contacts as Al/Si [2, 3], Au/Ta [4], or Mo [5]. Nevertheless, just a few authors have studied SiC growth on diamond [6, 7] most probably due to the difficulties related to this heterosystem. One of the main reasons is that diamond, as substrate, usually
    Physica Status Solidi (A) Applications and Materials 01/2014; · 1.46 Impact Factor
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    ABSTRACT: Metal-oxide-semiconductor structures with aluminum oxide as insulator and p-type (100) mono-crystalline diamond as semiconductor have been fabricated and investigated by capacitance versus voltage and current versus voltage measurements. The aluminum oxide dielectric was deposited using low temperature atomic layer deposition on an oxygenated diamond surface. The capacitance voltage measurements demonstrate that accumulation, depletion, and deep depletion regimes can be controlled by the bias voltage, opening the route for diamond metal-oxide-semiconductor field effect transistor. A band diagram is proposed and discussed.
    Applied Physics Letters 06/2013; 102(24). · 3.79 Impact Factor
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    ABSTRACT: The nanometer-range depth resolution of secondary ion mass spectrometry (SIMS) profiles in diamond was achieved by the determination of the depth resolution function (DRF). The measurement of this DRF was performed thanks to isotopic-enriched diamond delta structures composed of 12C and 13C. The artificial SIMS broadening observed on the 13C depth profiles of buried doped diamond epilayers was eliminated and replaced by a boxlike 13C depth profile. Applied to boron delta-doped diamond structures, this analysis has resolved edge widths close to 0.3 nm/dec, as compared with 1.5 nm/decade on the raw SIMS data.
    Applied Physics Express 04/2013; 6:045801. · 2.73 Impact Factor
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    ABSTRACT: Nanopores in insulating solid state membranes have recently emerged as potential candidates for sorting, probing and manipulating biopolymers, such as DNA, RNA and proteins in their native environment. Here a simple, fast and cost-effective etching technique to create nanopores in diamond membrane by self-assembled Ni nanoparticles is proposed. In this process, a diamond film is annealed with thin Ni layers at 800-850 °C in hydrogen atmosphere. Carbon from the diamond-metal interface is removed as methane by the help of Ni nanoparticles as catalyst and consequently, the nanoparticles enter the crystal volume. In order to optimize the etching process and understand the mechanism the annealed polycrystalline and nanocrystalline diamond films were analyzed by X-ray photoelectron spectroscopy (XPS), and the gas composition during the process was investigated by quadrupole mass spectrometer. With this technique, nanopores with lateral size in the range of 15-225 nm and as deep as about 550 nm in diamond membrane were produced without any need for lithography process. A model for etching diamond with Ni explaining the mechanism is discussed.
    Carbon 03/2013; 59:448-456. · 5.87 Impact Factor
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    ABSTRACT: The recent achievements in diamond devices technology, in particular the control of carrier density in diamond with a top gate in a MOS structure[1,2], opens the way for power electronic devices fabrication taking advantage of exceptional diamond properties. However, the design of such devices requires accurate electrical simulation, taking into account the specificities of this semiconductor. These are essential for understanding the device behaviour and anticipating its architecture. In this study, main equations governing the electronic properties of diamond were implemented in the Silvaco TCAD software suite (Atlas 2D). In particular, the boron ionization energy dependence in dopant concentration, the hole and electron concentration dependence in temperature and various effects influencing the hole and electron mobilities [3,4] were implemented. For each particular implemented model, a detailed comparison is provided between available measurements from the literature and fitted parameters in the numerical software. The chosen models and their fitted parameters are therefore provided. Details are also provided on the particularities introduced with numerical simulation of diamond electronic devices.
    Hasselt Diamond workshop 2013, SBDD XVIII, Hasselt, Belgium; 02/2013
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    ABSTRACT: Diamond is not only known for being the hardest gemstone but also for being the semiconductor having the highest calculated figures of merit (FOM). This comes from the unique physical properties of this material. Thus, it is predicted that diamond should exceeds silicon carbide (SiC) and galium nitride (GaN) in terms of low loss device and better compromises for on-state resistance versus breakdown voltage. However, in practice the applications of diamond devices are still limited and the performances are still not reaching the theoretical predictions. The question is then how to predict and evaluate diamond device performances themselves and in their environment. One of the possible answer is by using finite element based softwares. Few reports exist on unipolar diamond device modeling, and none on diamond bipolar device. The main limitations come from the lack of parameters implemented in the simulation tools together with the difficulties for modeling wide band gap semiconductor, i.e. extremely low carrier concentrations. In this study, we present the results on the first simulation of a diamond bipolar junction transistor electrical characteristics. The validation of the simulation is the first step towards the prediction of the architecture and behavior of future diamond devices.
    Wide Bandgap Power Devices and Applications (WiPDA), 2013 IEEE Workshop on; 01/2013
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    ABSTRACT: A simple, fast and cost-effective etching technique to create oriented nanostructures such as pyramidal and cylindrical shaped nanopores in diamond membranes by self-assembled metallic nanoparticles is proposed. In this process, a diamond film is annealed with thin metallic layers in a hydrogen atmosphere. Carbon from the diamond surface is dissolved into nanoparticles generated from the metal film, then evacuated in the form of hydrocarbons and, consequently, the nanoparticles enter the crystal volume. In order to understand and optimize the etching process, the role of different parameters such as type of catalyst (Ni, Co, Pt, and Au), hydrogen gas, temperature and time of annealing, and microstructure of diamond (polycrystalline and nanocrystalline) were investigated. With this technique, nanopores with lateral sizes in the range of 10-100 nm, and as deep as about 600 nm, in diamond membranes were produced without any need for a lithography process, which opens the opportunities for fabricating porous diamond membranes for chemical sensing applications.
    Nanotechnology 10/2012; 23(45):455302. · 3.84 Impact Factor
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    ABSTRACT: The temperature dependence of the hole sheet density and mobility of four capped delta boron doped [100]-oriented epilayers has been investigated experimentally and theoretically over a large temperature range (textlessequationtextgreater6 textlessfont face='roman'textgreaterKtextless/fonttextgreater<textlessfont face='roman'textgreaterTtextless/fonttextgreater<500 textlessfont face='roman'textgreaterKtextless/fonttextgreatertextless/equationtextgreater). The influence of the parallel conduction through the thick buffer layer overgrown on the diamond substrate was shown not to be negligible near room temperature. This could lead to erroneous estimates of the hole mobility in the delta layer. None of the delta-layers studied showed any quantum confinement enhancement of the mobility, even the one which was thinner than 2 nm.
    Applied Physics Letters 10/2012; 101(16):162101-162101-4. · 3.79 Impact Factor
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    ABSTRACT: Possible lattice incorporation sites for Ni in diamond have been investigated using ab initio density functional theoretical calculations. The results have been used to compute x-ray absorption near-edge structure spectra which were compared to spectroscopic measurements performed on a diamond single crystal grown at high pressure and high temperature in a nickel solvent. Ni at divacancy sites is proposed to be the most stable and probable configuration in this crystal.
    Physical review. B, Condensed matter 08/2012; 86(5). · 3.77 Impact Factor
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    ABSTRACT: A magneto-optical study of the 1.4 eV Ni color center in boron-free synthetic diamond, grown at high pressure and high temperature, has been performed in magnetic fields up to 56 T. The data is interpreted using the effective spin Hamiltonian of Nazar\'e, Nevers and Davies [Phys. Rev. B 43, 14196 (1991)] for interstitial Ni$^{+}$ with the electronic configuration $3d^{9}$ and effective spin $S=1/2$. Our results unequivocally demonstrate the trigonal symmetry of the defect which preferentially aligns along the [111] growth direction on the (111) face, but reveal the shortcomings of the crystal field model for this particular defect.
    Physical review. B, Condensed matter 03/2012; 86(4). · 3.77 Impact Factor
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    ABSTRACT: We demonstrate the coupling of single color centers in diamond to plasmonic and dielectric photonic structures to realize novel nanophotonic devices. Nanometer spatial control in the creation of single color centers in diamond is achieved by implantation of nitrogen atoms through high-aspect-ratio channels in a mica mask. Enhanced broadband single-photon emission is demonstrated by coupling nitrogen-vacancy centers to plasmonic resonators, such as metallic nanoantennas. Improved photon-collection efficiency and directed emission is demonstrated by solid immersion lenses and micropillar cavities. Thereafter, the coupling of diamond nanocrystals to the guided modes of micropillar resonators is discussed along with experimental results. Finally, we present a gas-phase-doping approach to incorporate color centers based on nickel and tungsten, in situ into diamond using microwave-plasma-enhanced chemical vapor deposition. The fabrication of silicon-vacancy centers in nanodiamonds by microwave-plasma-enhanced chemical vapor deposition is discussed in addition.
    Beilstein Journal of Nanotechnology 01/2012; 3:895-908. · 2.37 Impact Factor
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    Canadian Journal of Physics 02/2011; 69:357-360. · 0.90 Impact Factor
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    ABSTRACT: A method for obtaining a smooth, single crystal diamond surface is presented, whereby a sacrificial defective layer is created by implantation of a regular (4 nm roughness) Ib diamond plate. This was then graphitized by annealing before being selectively etched. We have used O þ at 240 keV, the main process variables being the ion fluence (ranging from 3 Â 10 15 to 3 Â 10 17 cm À2) and the final etching process (wet etch, H 2 plasma, and annealing in air). The substrates were characterized by atomic force microscopy, optical profilometry and white beam X-ray topography. The influence of the various process parameters on the resulting lift-off efficiency and final surface roughness is discussed. An O þ fluence of 2 Â 10 17 cm À2 was found to result in sub-nanometer roughness over tens of mm 2 . 1 Introduction The interest in boron-doped diamond for electronic devices is increasing because of its attractive electrical properties: wide band gap, high thermal conduc-tivity, high mobility, and high breakdown electric field. Recently, nanostructuring diamond monocrystalline plates into 2D (delta-doped layers, membranes) or 1D objects (pillars, suspended cantilevers) [1] is becoming increasingly relevant for a number of applications of this material (e.g., field effect transistors (FETs), sensors, and nanoelectro-mechanical systems). In particular, the d-doped diamond structure has been considered for some time because of its possible application as an electrical switch in FETs, expected to commute high power at high frequency. A d-doped diamond structure requires a very thin metallic boron-doped p þ layer ([B] pþ ! 5 Â 10 20 at cm À3), called the ''d-layer,'' intercalated between two low boron-doped layers (non-intentionally doped, NiD) ([B] NiD 1 Â 10 17 at cm À3). In previous studies [2], it has been shown that the single crystal diamond substrates play a very important role for the quality of the epitaxial growth and that they also have a significant influence on the electrical properties of the
    physica status solidi (a) 01/2011; 208:2057. · 1.21 Impact Factor
  • Wiebke Janssen, Etienne Gheeraert
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    ABSTRACT: In a top–down approach diamond nanowires (DNW) were fabricated by anisotropic oxygen plasma etching of undoped or boron doped polycrystalline diamond layers. Dewetting an evaporated metal film, resulting in randomly distributed metal droplets of 5–50nm in diameter, created the etching mask. This study focused on the investigation of the effect of the metal layer type, i.e., Al, Ti, Co, Ni, Cu, Pd, Pt and Au, and thickness on surface density, shape and size of the resulting droplets. Two dry etching techniques were studied: (1) Capacitively Coupled Plasma Reactive Ion Etching (CCP-RIE) and (2) Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE). Using CCP-RIE diamond etch rates were between 10nm/min and 50nm/min; however, diamond/Ni selectivity was not high enough to fabricate nanowires >longer than 250nm. ICP-RIE etching created tapered, high aspect diamond nanostructures at 1000W plasma power, 10W platen power for ion acceleration and long etching times (>40min) while preserving the mask. Anisotropy can be improved by the addition of Ar in the plasma and the reduction of the pressure. So far, vertically aligned diamond nanowires of 800nm in length were obtained by ICP-RIE etching in appropriate conditions.
    Diamond and Related Materials 01/2011; 20(3):389-394. · 1.71 Impact Factor
  • Wiebke Janssen, Sebastian Faby, Etienne Gheeraert
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    ABSTRACT: Diamond nanowires are fabricated in a bottom–up approach by anisotropic oxygen plasma etching. A hexagonally arranged network polystyrene spheres of 500 nm to 2 μm in diameter was deposited on diamond and served as shadow mask during 10 nm nickel evaporation. This led, after dewetting at 650 °C, to a hexagonal network of Ni droplets of 60 to 80 nm in diameter, and was used as etching mask to create the network of vertically aligned diamond nanowires. Influence of film thickness, annealing time, and polystyrene sphere diameter were studied. The plasma etching process was also applied to fabricate diamond microdisks on silicon post.Research highlights► Bottom-up fabrication of diamond nanowires. ► Self-alignment of Ni nano-droplets on diamond surface. ► Anisotropic Diamond etching by Reactive Ion Etching.
    Diamond and Related Materials 01/2011; 20:779-781. · 1.71 Impact Factor
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    ABSTRACT: Chemical Vapor Deposited (CVD) diamond has great advantages for use as thermoluminescent dosimeters in radiotherapy environment because of the reproducible high quality and controlled doping. This study compares CVD diamond Thermally Stimulated Luminescence response to that of a classical ionization chamber. Clinically-relevant features like the depth–dose distributions as well as the absorbed dose profile are investigated for a 6 MV photon beam and a 6MeV electron beam. Moreover electron beam cartography has been controlled by means of CVD diamonds. Reproducibility and repeatability of TL measurements are satisfying and a good TL sensitivity to both electron and photon beams is clearly shown. Comparing the TL responses presented here to the ionization chamber underline the very promising behavior of CVD diamonds, particularly in high dose gradient areas.
    Diamond and Related Materials 01/2011; 20(4):520-522. · 1.71 Impact Factor
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    ABSTRACT: Nickel doped single crystal diamond layers were grown by microwave-plasma enhanced chemical vapour deposition. Optical emission spectroscopy (OES) utilised during growth proved that the organometallic compound nickelocene is an applicable nickel source. It was possible to produce stable and adjustable nickel OES signals during growth by altering the flux of the nickelocene carrier gas. The successful incorporation of nickel into the diamond layers was verified by secondary ion mass spectrometry. Cathodoluminescence (CL) was applied to reveal optically active defects related to nickel. The signature of substitutionally incorporated nickel, namely the nickel related 1.4 eV centre, as well as the 2.369 and 1.563 eV centres were observed in CL. The latter is supposed to be a single-photon emitter on the basis of a nickel–nitrogen defect centre.
    Physica Status Solidi (A) Applications and Materials 08/2010; 207(9):2054 - 2057. · 1.46 Impact Factor

Publication Stats

752 Citations
204.97 Total Impact Points

Institutions

  • 2014
    • Institut Néel
      Grenoble, Rhône-Alpes, France
    • University of Grenoble
      Grenoble, Rhône-Alpes, France
  • 1992–2014
    • French National Centre for Scientific Research
      • Institut Néel
      Lutetia Parisorum, Île-de-France, France
  • 1996–2013
    • University Joseph Fourier - Grenoble 1
      • Institut Néel
      Grenoble, Rhône-Alpes, France
  • 2002
    • Technische Universität München
      • Walter Schottky Institut (WSI)
      München, Bavaria, Germany
  • 2000
    • Tsukuba Research Institute
      Edo, Tōkyō, Japan
  • 1999
    • Rutgers, The State University of New Jersey
      New Brunswick, New Jersey, United States
  • 1994
    • King's College London
      • Department of Physics
      London, ENG, United Kingdom
    • Atomic Energy and Alternative Energies Commission
      • Centre d'Etudes de Saclay
      Gif-sur-Yvette, Ile-de-France, France