L. Buchaillot

ELVESYS Innovation Centre, Lutetia Parisorum, Île-de-France, France

Are you L. Buchaillot?

Claim your profile

Publications (144)128.45 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: In the present work, AlGaN/GaN high electron mobility transistors (HEMTs) have been grown with very thin buffer layers on silicon substrates in view of developing nano electromechanical systems (NEMS) for sensors applications. To ensure transducer operation in the MHz range together with low mechanical stiffness, epitaxial structures with thickness below 1 μm have to be developed. We report on the evolution of the material and electrical properties of AlGaN/GaN HEMTs with thicknesses varying from 2 μm to 0.5 μm. The set of parameters obtained includes in-plane Young modulus of 250 GPa in association with carrier density of 6 × 1012 cm−2 and mobility above 1000 cm2 V−1 s−1. The resulting behavior of demonstration transistors validates these epilayers for electromechanical resonators operation.
    Semiconductor Science and Technology 11/2014; 29(11). · 1.92 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Most of commercial Atomic Force Microscope (AFM) oscillating probes use micrometric cantilevers that can make measurement with piconewton force resolution under vacuum. However, the flexure vibration cantilevers suffer from a degradation of both resonance frequency and quality factor when operating in liquids. Moreover, the additional laser set-up for amplitude detection also limits the integration and miniaturization of the resonator structure. In order to overcome these difficulties, we propose to replace cantilevers by bulk mode, in-plane vibrating MEMS resonators with integrated transduction methods.
    2014 IEEE International Frequency Control Symposium (FCS); 05/2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A new concept of atomic force microscope (AFM) oscillating probes using electrostatic excitation and piezoresistive detection is presented. The probe is characterized by electrical methods in vacuum and by mechanical methods in air. A frequency-mixing measurement technique is developed to reduce the parasitic signal floor. The probe resonance frequencies are in the 1 MHz range and the quality factor is measured about 53 000 in vacuum and 3000 in air. The ring probe is mounted onto a commercial AFM set-up and topographic images of patterned sample surfaces are obtained. The force resolution deduced from the measurements is about 10 pN Hz−0.5.
    Journal of Micromechanics and Microengineering 01/2013; 23(3):035016. · 1.79 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We report on a new concept of Atomic Force Microscope (AFM) oscillating probes using dog-bone resonator with thermal excitation and piezoresistive detection. The resonance frequency is 5.4 MHz and the quality factor is measured about 4,000 in air. AFM images are obtained over PMMA resist sample and the force resolution deduced from the measurement is about 320 pN/Hz0.5.
    Micro Electro Mechanical Systems (MEMS), 2013 IEEE 26th International Conference on; 01/2013
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A concept of atomic force microscopy (AFM) oscillating sensors using electromechanical silicon microresonators is presented, and imaging capabilities are demonstrated. The microresonators are designed to feature MHz resonance frequencies, and they are batch fabricated using standard silicon microtechnologies. Integrated capacitive transducers allow to drive the resonator and to sense its vibration amplitude. A nanotip is located at a maximum of displacement for sensing near-field forces when interacting with a surface. The device has been mounted on a commercial AFM setup through a dedicated probe holder and a preprocessing electronic circuit. Experiments show that intermittent contact AFM is possible with a tip vibration amplitude of a few nanometers. AFM images have been acquired on silicon micro and nanopatterns. A force resolution of 0.2 $\hbox{nN}/ \surd\hbox{Hz}$ is deduced from the measurements.$\hfill$ [2011-0210]
    Journal of Microelectromechanical Systems 04/2012; 21(2):385-397. · 2.13 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We investigate the size distribution of electrically charged nanodroplets using atomic force microscopy (AFM). The droplets were generated using nano- and micro-scale silicon tips. A brief voltage pulse results in a “snapshot” of charged nanodroplets on a Cr surface. AFM of the traces left by the nanodroplets revealed that certain droplet diameters are favored suggesting droplet fission due to Rayleigh instability at nanometer length scales. The most occurring droplet diameters are 85.9(4.1) nm and 167.1 nm (9.7 nm) for nano- and micro-scale tips, respectively.
    Applied Physics Letters 02/2012; 100(7). · 3.52 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigate the response of a GaN microelectromechanical resonator where the strain detection is performed by a resonant high-electron mobility transistor (R-HEMT). The R-HEMT gate located above the 2-DEG (two-dimensional electron gas) appears to enable a strong control of the electromechanical response with a gate voltage dependence close to a transconductance pattern. A quantitative approach based on the mobility of the carriers induced in the device by the piezoelectric response of the GaN buffer is proposed. These results show for the first time the electromechanical transconductance dependence versus external biasing and confirm that active piezoelectric transduction is governed by the AlGaN/GaN 2-DEG transport properties.$\hfill$ [2010-0210]
    Journal of Microelectromechanical Systems 01/2012; 21(2):370-378. · 2.13 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: For the first time, 100nm side DNA origami squares have been imaged using 10.9MHz laserless AFM MEMS probe. This sensor takes advantage of the high resonance frequency of a silicon bulk mode resonator integrating a nano-tip fabricated in batch process. After integration in a commercially available AFM set-up with a modified probe holder, the AFM MEMS probe has demonstrated its capability of soft matter imaging.
    Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) 01/2012;
  • [Show abstract] [Hide abstract]
    ABSTRACT: A new concept of Atomic Force Microscope (AFM) oscillating probes using electrostatic excitation and piezoresistive detection is presented. The probe is characterized by electrical methods in vacuum chamber and by mechanical methods in air. The frequency-mixing measurement technique is developed to reduce the parasitic signal level. These probes resonance frequencies are in the 1MHz range and the quality factor is measured about 53,000 in vacuum and 3,000 in air. The force resolution deduced from the measurements is about 8 pN/Hz0.5.
    Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) 01/2012;
  • [Show abstract] [Hide abstract]
    ABSTRACT: A new concept of Atomic Force Microscope (AFM) oscillating probes using electrostatic excitation and piezo-resistive detection is presented. The probe is characterized by electrical methods in a vacuum chamber and by mechanical methods in air. The frequency-mixing measurement technique is developed to reduce the parasitic signal level. These probes resonant in the 1MHz range and the quality factor is measured about 53,000 in vacuum and 3,000 in air. The ring probe is mounted onto a commercial AFM set-up and the surface topography of PMMA sample (2 μm square) is obtained. The force resolution deduced from the measurements is about 10 pN/Hz0.5.
    Manipulation, Manufacturing and Measurement on the Nanoscale (3M-NANO), 2012 International Conference on; 01/2012
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents strain measurements using digital image correlation of common microelectronic metal nanofilms deposited onto a polymer substrate (SU-8), which has applications in flexible electronics and nano/microsystems reliability analysis. The novel experimental method is based on digital image correlation coupled with microtensile test apparatus for the in situ investigation of the deformation behaviour of the deposited thin films under uniaxial tensile loading. One of the key features of the method is the real-time two-dimensional strain field measurements on a bare thin film surface, during the deformation process, without any initial speckle or grid deposition. The outstanding performances of the method, having a spatial resolution of 0.7 µm, allow one to envisage further studies related to the understanding of the mechanical behaviour of such thin films and, in particular, the damage localization process.
    Journal of Micromechanics and Microengineering 11/2011; 21(12):125005. · 1.79 Impact Factor
  • E. Herth, E. Algré, B. Legrand, L. Buchaillot
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents the optimization of polysilicon doping and metallization to form ohmic contact with etching resistance. Indeed, polysilicon doped by ion implantation and ohmic contacts are an important and interesting part of integrated circuit technology or MEMS and NEMS. LPCVD-polysilicon doping parameters, such as ion energy, dose, and annealing were investigated. In particular a superficial implantation realized after a deep implantation enables one to slightly decrease the polysilicon resistivity while the contact resistance is reduced. And ohmic contacts with wet etching resistance were realized by depositing the different metallization stacks. We demonstrate that ohmic contact pad Cr/Pt/Au has provided a good adhesion on LPCVD-polysilicon after wet etching.
    Microelectronic Engineering 05/2011; · 1.22 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We report here on high resonance frequency AFM probes based on MEMS bulk mode resonators. They consist on silicon ring resonators with capacitive transducers vibrating in the in-plane elliptic mode. Nano-tips placed at the maximum of vibration are fabricated in batch process. After electrical and optical characterizations, chips supporting the resonator and the prominent tip are extracted from the wafer. Next, the AFM nanoprobes are integrated in a commercially available AFM set-up with a modified probe holder. Experimental results of high resonance frequency AFM images are presented.
    Micro Electro Mechanical Systems (MEMS), 2011 IEEE 24th International Conference on; 02/2011
  • [Show abstract] [Hide abstract]
    ABSTRACT: The properties of a new class of electromechanical resonators based on GaN are presented. By using the two-dimensional electron gas (2-DEG) present at the AlGaN/GaN interface and the piezoelectric properties of this heterostructure, we use the R-HEMT (Resonant High Electron Mobility Transistor) as an active piezoelectric transducer up to 5MHz. In addition to the amplification effect of piezoelectric detection, we show that the active piezoelectric transduction has a strong dependence with the channel mobility that is controlled by a top gate. This allows to envision highly tunable sensors with co-integrated HEMT electronics.
    Micro Electro Mechanical Systems (MEMS), 2011 IEEE 24th International Conference on; 02/2011
  • Source
    G. Guisbiers, E. Herth, L. Buchaillot
    [Show abstract] [Hide abstract]
    ABSTRACT: The mechanical properties (Young’s modulus, hardness, wear resistance) of aluminium nanofilms on silicon substrate are studied. Size effect on these mechanical properties are exhibited. Young’s modulus, hardness and wear resistance increases when the thickness is reduced. Experimental investigations have been led by atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nanoindentation. Compared to the bulk values, hardness and wear resistance of one aluminium nanofilm (thickness = 100 nm) have increased by a factor ∼7 whereas the Young’s modulus only increased by a term ∼15%. By comparing mechanical properties between high and low melting point materials, we conclude that high melting point materials have a decreasing behaviour of the Young’s modulus with size whereas low melting point materials have an increasing one.
    Microelectronic Engineering. 01/2011;
  • [Show abstract] [Hide abstract]
    ABSTRACT: The history of MEMS resonators other than comb-drive is fairly short, 15 years at most. At the beginning, researchers together with engineers had the dream to replace quartz by silicon and they started working on resonators designed for filter application in cell phones. Today, MEMS resonators are surpassed by bulk acoustic wave technology and confined to time reference application. A couple of years ago, we decided the reorientation of our work on MEMS resonators towards atomic force microscopy (AFM) by fabricating integrated probes. In the World, besides US groups, like the Veeco group at Santa-Barbara, which does a lot of work for the AFM in liquid environment, there are still a few teams that aim to use dynamic AFM in liquid. The NanoScience Center from Munster (Resp. Fuchs) working with a private company (Atomic Force) has developed a signal processing that produces an artificial low damping coefficient in fluid. Also, it is worth to note that numerous teams from Japan are doing much effort to achieve an AFM oscillating system in liquid environment. For example, the Kawakatsu's group is focused on the development of an AFM in water with an oscillator vibrating at 20 MHz. Ando's Group has successfully imaged myosin motion onto a mica substrate with levers vibrating at 450 kHz (1 MHz in air) with 12 images/second within a 250 nm scanning window. High aspect ratio tip fabrication can be hardly achieved with such small lever dimensions. In order to clear this technological lock, deep changes are required. A paper reporting a joint study from Georgia Tech and Stanford [Onaran et al., Rev. Scientific Instruments 77 023501 2006]has shown an AFM tip mounted on a vibrating membrane. Using carefully designed micromachined mechanical structures with spring constants in the 1 N/m range and noise levels down to 10 fm/√Hz, they achieved piconewton force resolution with 10 kHz measurement bandwidth with this device. The dynamic modes of the AFM allow measurement of force variations under the picoNewton range. That is the reason why so many labs try to use the oscillating modes to probe soft matter or biological nanosystems dynamics in liquid environment. At present, these attempts face the difficulty of the liquid viscosity which dampens the oscillating cantilever. In order to minimize the hydrodynamic drag, we propose to change the overall oscillator and to choose an oscillation mode that reduces the liquid velocity gradient around the resonator. More precisely, the project aims to develop GHz MEMS/NEMS sensors for a new generation of high sensitivity Atomic Force Microscopes (AFM). This AFM will be a tool for in situ imaging of biological and chemical systems with a resolution better than the nanometer and the possibility of kinetic spectroscopy in liquids. In addition, it is intended to batch-fabricate the device in order to ease the possible industrial transfer thanks to the cost-effective approach.
    01/2011;
  • [Show abstract] [Hide abstract]
    ABSTRACT: A new concept of Atomic Force Microscope (AFM) oscillating probes using electrostatic excitation and piezo-resistive detection is presented. The probe is characterized by electrical methods in vacuum chamber and by mechanical methods in air. The mixer measurement technique is developed to reduce the parasitic signal level. These probes resonance frequencies are in the 1MHz range and the quality factor is measured about 53,000 in vacuum and 3,000 in air. The force resolution deduced from the measurements is about 8 pN/Hz0.5 .
    ASME 2011 International Mechanical Engineering Congress and Exposition; 01/2011
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper reports on the description of a new high force-resolution microgripper with large jaw displacement, electrostatically actuated by a comb-drive and instrumented with an integrated differential capacitive displacement sensor. This microgripper has been non-intuitively designed using a multi-objective optimization method, to reach the best compromise between chosen performance criteria. It has been modeled and fabricated using silicon micro-technology. The theoretical gripping force resolution obtained is 78 pN along the direction of the mobile tip displacement. This performance is many times of magnitude better than the monolithically fabricated MEMS based grippers mentioned in the literature. First experimental characterization tests have been conducted and show good agreement with the expected theoretical performances.
    2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2011, San Francisco, CA, USA, September 25-30, 2011; 01/2011
  • [Show abstract] [Hide abstract]
    ABSTRACT: The properties of a new class of electromechanical resonators based on GaN are presented. By using the flexural modes of a doubly clamped beam, the two-dimensional electron gas (2-DEG) present at the AlGaN/GaN interface can be modulated by a field effect arising from the GaN buffer piezoelectricity. This leads to active piezoelectric transducers for which we show experimental results with detailed bias condition studies up to 10 MHz. Associated with modeling of the transduction physics, this allows explaining how the 2-DEG properties lead to the transconductance effect in the electromechanical domain.
    01/2011;
  • Source
    G. Guisbiers, E. Herth, L. Buchaillot, T. Pardoen
    [Show abstract] [Hide abstract]
    ABSTRACT: The fracture toughness, hardness, and Young’s modulus of tantalum thin films are investigated based on nanoindentation measurements. A lower estimate of the fracture toughness of a 100 nm tantalum film is 0.28±0.07 MPa m1/2. The hardness increases when reducing the film thickness whereas Young’s modulus decreases slightly. More precisely, the hardness of the 100 nm thick film is four times higher than the bulk behavior. A simple theoretical model, based on the connection between Young’s modulus and melting temperature, predicts an inverse grain size variation in Young’s modulus confirmed by experiments.
    Applied Physics Letters 10/2010; 97(14). · 3.52 Impact Factor

Publication Stats

503 Citations
128.45 Total Impact Points

Institutions

  • 2010
    • ELVESYS Innovation Centre
      Lutetia Parisorum, Île-de-France, France
  • 2007
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
  • 1997–2006
    • The University of Tokyo
      • Institute of Industrial Science
      Tokyo, Tokyo-to, Japan
  • 2000
    • University of Lille Nord de France
      Lille, Nord-Pas-de-Calais, France