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The generation and transfer of ultra-stable microwave signals are of paramount importance in numerous applications spanning from radar systems to communications and metrology. We demonstrate residual phase noise mitigation at 10 GHz of a directly modulated laser system through active control of the laser bias current. The latter is tuned to a finely selected point, where the current-to-phase dependence, measured at several microwave power and frequency values, is maximized. A residual phase noise of − 113 d B r a d 2 / H z at 1 Hz offset frequency from a 10 GHz carrier, with a fractional frequency stability of 1.2 × 10 − 16 at 1 s and below 10 − 19 at 10 5 s , is measured. These performances are compliant with the transfer of the most stable microwave signals available to date, obtained with cryogenic sapphire oscillators or combs locked to cavity-stabilized lasers. This approach is of interest for the distribution of ultra-stable microwave signals in a very simple photonic configuration.

We have investigated the self-assembly of a strong dipolar molecule (LDipCC) on the semiconducting Si(111)-B surface with scanning tunneling microscopy (STM), density functional theory (DFT) calculations and STM simulations. Although the formation of an extended two-dimensional network was clearly revealed by STM under ultra-high vacuum, the assignment of a specific STM signature to the different terminal groups from the LDipCC molecular unit required a complete analysis by numerical simulations. The overall observed assembly is explained in terms of STM contrasts associated with the molecular structure of LDipCC and the molecule-surface interactions. To distinguish the relative arrangement of the dipolar molecules within the assembly, a rational combination of experimental results and electronic structure calculations allows us to identify a single adsorbed LDipCC phase in which the molecular dipoles are homogeneously arranged into a parallel fashion on the Si(111)-B surface.

International audience; The growth of an extended supramolecular network using dipolar molecules as the building blocks is of great technological interest. We investigated the self-assembly of a dipolar molecule on an Au(111) surface. The formation of an extended two-dimensional network was demonstrated by scanning tunnelling microscopy under ultra-high vacuum and explained in terms of molecule–molecule interactions. This 2D-network is still stable under the pressure of one atmosphere of nitrogen, which demonstrated its interest for the development of submolecular-precisely polyfunctional smart surfaces.

International audience; The monitoring of heat flux is becoming more and more critical for many materials and structures approaching nanometric dimensions. Scanning Thermal Microscopy (SThM) is one of the tools available for thermal measurement at the nanoscale and requires calibration. Here we report on a micro-hotplate device made of a platinum heater suspended on thin silicon nitride (SiN) membranes integrating specific features for SThM calibration. These heated reference samples can include a localized resistive temperature sensors (RTD) or standalone platinum membranes (typically 10 × 10 μm2) on which the temperature can be measured precisely. This functional area is dedicated to (1) estimate the thermal resistance between the SThM tip and hot surface contact; and to (2) evaluate the perturbation induced by the probe on the heat dissipation when the contact measurement is performed. The thermal design of these low-power calibration chips, their fabrication, including sensitive RTDs patterned using e-beam technology, as well as their electro-thermal and electro-mechanical characterizations are presented. Robust operation of the chips up to 500 °C has been demonstrated with their membrane mechanically stable up to 250 °C and a low-power consumption of 16 mW at this operating temperature. The temperature mapping of the active areas was performed using two physical principles: local SThM temperature measurement using a thermocouple-based micro-probe and optical imaging using Near-Infrared (NIR) microscopy. Measurements coupling on one hand SThM probe and the integrated RTD and, on the other hand, SThM probe with optical imaging, validated the functionality of the calibration chips. The latter open new perspectives in the calibration of SThM probes.

A grating structure serves as the most fundamental element of inter-digital transducers (IDTs). IDTs are used for excitation and detection of surface acoustic waves (SAW) in Ultra wide band (UWB) SAW devices. Reflections on the metal fingers greatly affect the functionality of IDTs, and thus that of the SAW devices they are used in. Hence, this effect has been studied extensively and several models and theories have been proposed for this purpose. The signal properties of IDT devices can be controlled by varying several parameters like the number of fingers (electrodes) of the IDT or the spatial distribution of the pitch of the array of fingers. Here, we wish to study the generation and propagation of SAW inside a chirped IDT.

International audience; The measurement of the displacements caused by the propagation of a short pulse of surface acoustic waves on a solid substrate is investigated. A stabilized time-domain differential interferometer is proposed, with the surface acoustic wave (SAW) sample placed outside the interferometer. Experiments are conducted with surface acoustic waves excited by a chirped interdigital transducer on a piezoelectric lithium niobate substrate having an operational bandwidth covering the 200–400 MHz frequency range and producing 10-ns pulses with 36 nm maximum out-of-plane displacement. The interferometric response is compared with a direct electrical measurement obtained with a receiving wide bandwidth interdigital transducer and good correspondence is observed. The effects of varying the path difference of the interferometer and the measurement position on the surface are discussed. Pulse compression along the chirped interdigital transducer is observed experimentally.

International audience; Optical interferometry is a well-known technique for studying wave propagation and is often preferred over other methods for its highprecision in studying wave profiles, amplitude and phase variations, standing wave patterns, group delay measurements, etc., of waves like surface acoustic waves, Scholte- Stoneley waves, dilatational waves, etc... In the past, different interferometer setups have been employed to detect and measure surface acoustic waves. Differential interferometers have proved to be useful in various fields, like piezoelectric thin film characterization, angular measurements of the order of nano-radians and displacement measurements in the picometre range, of acoustic signals, etc. High sensitivity to the phase and amplitude of the acoustic signals and easy calibration of the setup are the key advantages of a differential interferometer. They are a solution to a common disadvantage of interferometry, i.e., path length sensitivity. Our objective is to construct an interferometer that allows to study transient surface acoustic waves in the time domain.The differential interferometer used in this work is an extended version of a Michelson’s interferometer, where the laser beamreflected from the SAW device, carrying phase and amplitude information of the surface acoustic waves, is divided into two orthogonally polarized beams that traverse different arm lengths, and are recombined using a polarizing beam splitter. This causesshearing in the time domain, with the change in phase along the two arms of the interferometer being a function of the path lengths ofthe two orthogonal beams causing interference. The signal received on the photodiode as a function of time is proportional to thenormal velocity at the surface of the sample. The experimental setup is designed to measure displacements of the order of a fewnanometers, of a SAW device producing transient short pulses with a chirped input IDT. An output IDT with only one finger-pair isused for comparison purposes.The setup being extremely sensitive, requires noise calibration. In order to improve the alignment and test the accuracy of theresponse, different parameters of the experimental setup are varied. An input chirp is used to excite SAW pulses within a frequencyrange of 200 – 400 MHz. The Fourier transform limited pulse duration is about 5 ns. The response measured at the output IDT,directly and by using the interferometer setup, are compared, and the change in amplitude and phase for the two measurements arestudied for two cases: varying position of focus between the two IDTs on the SAW device, and varying path length.

International audience; We report on the development of a vibrometer for in-plane motion which is particularly suitable for Micro Electro Mechanical System (MEMS) samples. The system combines a conventional microscope, coherent electronics and a Full Frame CCD camera. Stroboscope lighting allows the system to freeze the motion. The obtained images correspond to different phases of the sample motion. Different subpixel motion measurement algorithms are compared in terms of precision and computation time. An algorithm that we specially design for this application proved to be the best. It is based on the shift Fourier theorem and uses first harmonics, where most energy is present. Thus the system allows computing the phase and magnitude of the sample displacement. With the system we can obtain a measurement resolution of 100 pm demonstrated on the AFM cantilever vibrations measurement. The effect of the edge roughness was studied. It decreases the performance of the algorithm but roughness is very low on most MEMS applications. This method based on a CCD camera, is very well suited for measuring in-plane MEMS vibration since it does not require surface roughness for scattering the light as with the speckle methods (for example). It can quickly obtain full field motion, with a high precision. Furthermore, the used algorithm is simple, fast and very noise insensitive.

International audience; A novel probe for scanning thermal microscope using a micro-thermocouple probe placed on a Quartz Tuning Fork (QTF) is presented. Instead of using an external deflection with a cantilever beam for contact detection, an original combination of piezoelectric resonator and thermal probe is employed. Due to a non-contact photothermal excitation principle, the high quality factor of the QTF allows the probe-to-surface contact detection. Topographic and thermal scanning images obtained on a specific sample points out the interest of our system as an alternative to cantilevered resistive probe systems which are the most spread.

We present two aspects of modeling and design of a Scanning Thermal Microscopy (SThM) probe built by microfabrication techniques. An optimized design based on a full parametrization of its geometry is calculated using a multi-criteria optimization technique after a drastic selection of the most sensitive geometrical parameters. The optimization is carried out in the static regime. We also report a new time-space multi-scale model of the probe operating in active mode and heated with a combination of DC and modulated harmonic current sources, a case where the simulation takes too long to be used in a regular design process. The model derivation is based on an asymptotic methods related to high frequency periodic source. Precisely, the model distinguishes between two time scales and two space scales related to the low and high frequency phenomena. Simulation results show the potential of the model in terms of accuracy and computation speed and are compared to experimental results.

We present a multi-scale model of a probe for scanning thermal microscopy. The probe is built by microfabrication techniques. In active mode, it is supplied by a source of harmonic and/or continuous current and the tip temperature is measured after a lock-in amplifier. The model distinguishes two time scales and two space scales. Simulation results show the potential of the model in terms of accuracy and computation speed and they are compared to experimental results. Finally, a temperature control law constructed from this model is stated.

This paper describes the development of a scanning heterodyne interferometer for acoustic wave energy mapping. A robust optical double pass interferometer setup is presented, allowing absolute phase and absolute magnitude measurements of the out-of-plane vibration component witin a 5 to 1200 MHz frequency range, only limited by the photodetector bandwidth. By using a dedicated high frequency demodulator, the system is insensitive to the low-frequency mechanical vibration. The system is here used on single-port Surface Acoustic Wave, allowing for the identification of energy distribution as a function of operating frequency and the acoustic velocity over the Bragg mirrors surrounding the resonator. We envision such an instrument as a tool for assessing acoustic energy confinement allowing for optimizing resonator quality factors aimed at providing improved frequency source stability.

We report on the design, fabrication and characterization of polymeric printed micro-hotplates for gas sensing applications. The micro-hotplates sensing platforms have been realized by inkjet-printing. The silver nanoparticles-based heater and the interdigitated electrodes were both printed with a dielectric interlayer of laminated dry photoresist between them. The devices were completed with the deposition of a polyaniline sensing layer doped with polymeric acids, which when operated at 80°C, resulted in sensitive and reliable resistive ammonia sensor fabricated on flexible foil.

The scanning thermal microscope (SThM) has become a versatile tool for local surface temperature mapping or measuring thermal properties of solid materials. In this article, we present recent improvements in a SThM system, based on a micro-wire thermocouple probe associated with a quartz tuning fork for contact strength detection. Some results obtained on an electrothermal micro-hotplate device, operated in active and passive modes, allow demonstrating its performance as a coupled force detection and thermal measurement system.

A scanning thermal microscope working in passive mode using a micronic thermocouple probe is presented as a quantitative technique. We show that actual surface temperature distributions of microsystems are measurable under conditions for which most of usual techniques cannot operate. The quantitative aspect relies on the necessity of an appropriate calibration procedure which takes into account of the probe-to-sample thermal interaction prior to any measurement. Besides this consideration that should be treated for any thermal contact probing system, the main advantages of our thermal microscope deal with the temperature available range, the insensitivity to the surface optical parameters, the possibility to image DC, and AC temperature components up to 1 kHz typically and a resolution limit related to near-field behavior. (C) 2013 AIP Publishing LLC.

5 pages; International audience; This paper reports on a method which allows a decrease in the minimal detectable temperature in visible and near infrared thermography. This original method permits an increase in the thermal sensitivity without loss of good spatial resolution. It is based on a binning operation and a super-resolution algorithm. The radiometric model and super-resolution method are presented. Measurements on two different samples show the enhancement of the thermal sensitivity and the capability of the method. Finally, the authors propose different ways in which the method can be applied. © 2009 American Institute of Physics.

International audience; This communication reports on the design of ultra-low power micro-hotplates on polyimide (PI) substrate based on thermal simulations and characterization. The goal of this study was, by establishing a simulation model for very small scale heating elements, to decrease the power consumption of PI micro-hotplates to few mWs to make them suitable for very low-power applications. To this end, the mean heat transfer coefficients in air of the devices were extracted by finite element simulations combined with very precise thermographic measurements. A simulation model was implemented to investigate both the influence of the hotplates' downscaling and the bulk micromaching of the polyimide substrate to lower their power consumptions. Simulations were in very good agreement to the experimental results. The main parameters influencing significantly the power consumption at such dimensions were identified and guidelines have been established allowing the design of very small (15×15 μm2) and ultra-low power heating elements (6 mW at 300°C). These very low-power heating structures could allow the realization of flexible sensors (gas, flow, wind) for applications in autonomous wireless sensors networks or RFID applications and make them compatible with large scale production on foil such as roll to roll or printing processes.

Since local thermal probing has become a major tool for studying transport phenomena at micro- and nanoscale levels, the fundamental aspect of the interaction between the tip of the probe and the sample has remained the key point on which any quantitative measurement relies. In this paper we present results on thermal resistances involved in the contact mechanism of a microthermocouple cantilever probe that is used to scan the surface of a microhotplate at different levels of temperature. We point out the potential of such an active microsystem as an efficient calibration tool for near-field thermal probes. Copyright © 2008 by ASME.

International audience; Accurate estimation of displacement between successive images is a significant topic in the measurement of in-plane vibrations of microscopic objects such as micro-actuators. Actual subpixel motion estimation algorithms require the interpolation of interpixel values which undesirably increases the overall complexity and data flow and deteriorates estimation accuracy. Methods that do not use interpolation for achieving subpixel accuracy are scarcer in the literature. One approach for subpixel movement estimation without interpolation is based on phase correlation algorithm. This algorithm estimates the relative shift between two image blocks by means of a normalized cross-correlation function computed in the 2-D spatial Fourier domain. Indeed, the method is based on the Fourier shift theorem. The cross power spectrum of two images, containing subpixel shifts, is a polyphase decomposition of a Dirac delta function. By estimating the sum of polyphase components one can then determine subpixel shifts along each axis. Phase correlation is the state of the art for interpolation-free subpixel shift measurement between two frames, but this method is strictly limited to subpixel shifts. So, we have implemented this method using a standard optical microscope in order to observe subpixel translations with high spatial resolution measurements (down to 1 nm in the best cases). In this paper, we propose an application of this method to characterize the vibration mode shapes of a small silicon beam used in near-field acoustic microscopy. Harmonic movements of a few tens of nanometers are measured and presented.

International audience; We report on the dynamic and static thermal characterization of microsystems using a visible and near-infrared (NIR) thermography system based on a low-cost standard CCD sensor. The interest of this method is that it is possible to obtain a true spatial resolution better than 500 nm, which is necessary in high spatial resolution applications (microsystem applications). Another interesting point of this optical method is that the temperature error versus the emissivity error is always very low (compared to infrared thermography). We show, in this study, that this behavior originates in the high sensitivity of Planck's law in this wavelength range (compared to infrared range). Thus, we demonstrate the principal advantages of this method for micromachined heater application. Thermal measurements (in dynamic and static modes) were performed on micro-heaters commonly used in microsystems, platinum- and silicon-based micromachined heaters. The results show the capability of the method in terms of the thermal resolution and spatial resolution as well as the capacity to quickly obtain static and dynamic thermal images of the studied sample.

International audience; Using near-infrared thermography microscopy and a low-cost charge-coupled device (CCD) camera, we have designed a system which is able to deliver quantitative submicronic thermal images. Using a theoretical model based on Planck's law and CCD sensor properties allowed us to determine a minimal theoretical detection temperature and an optimal temperature sensitivity of our system. In order to validate this method, we show a good relationship between a theoretical study and a thermal measurement of a microsample.

International audience; A photo-thermal excitation of a Quartz Tuning Fork (QTF) for topographic studies is introduced. The non-invasive photo-thermal excitation presents practical advantages compared to QTF mechanical and electrical excitations, including the absence of the anti-resonance and its associated phase rotation. Comparison between our theoretical model and experiments validate that the optical transduction mechanism is a photo-thermal rather than photo-thermoacoustic phenomenon. Topographic maps in the context of near-field microscopy distance control have been achieved to demonstrate the performance of the system.

Local thermal probing has become a major tool for studying transport phenomena at micro and nanoscale levels, detecting hot spots and failures of microelectronic devices or measuring surface temperature distribution at these scales. If contact point measurement of a local tip is expected to provide the best spatial resolution, the fundamental aspect of the interaction between the probe tip and the sample remains the key point on which any quantitative measurement relies. We focus on the calibration procedure that will allow measuring the thermal response (error) of a contact probe used for temperature measurement on a surface. For this purpose, a micro-hotplate made of platinum heater suspended on thin silicon nitride (SiN) membrane represents an interesting tool. The objective is to develop heated reference samples with localized temperature sensors embedded on its surface to probe the temperature during the probe contact. We report on the thermal design of low-power calibration chip and the first results obtained when contacting wire based micro-Thermocouple Scanning Thermal Microscope (SThM) probes. © 2015 IEEE.

International audience; Conducting polyaniline-based chemiresistors on printed polymeric micro-hotplates were developed, showing sensitive and selective detection of ammonia vapor in air. The devices consist of a fully inkjet-printed silver heater and interdigitated electrodes on a polyethylene naphthalate substrate, separated by a thin dielectric film. The integrated heater allowed operation at elevated temperatures, enhancing the ammonia sensing performance. The printed sensor designs were optimized over two different generations, to improve the thermal performance through careful design of the shape and dimension of the heater element. A vapor-phase deposition polymerization technique was adapted to produce polyaniline sensing layers doped with poly(4-styrenesulfonic acid). The resulting sensor had better thermal stability and sensing performance when compared with conventional polyaniline-based sensors, and this was attributed to the polymeric dopant used in this study. Improved long-term stability of the sensors was achieved by electrodeposition of gold on the silver electrodes. Response to sub-parts-per-million concentrations of ammonia even under humid conditions was observed.

International audience; The design of ultra-low power micro-hotplates on a polyimide (PI) substrate supported by thermal simulations and characterization is presented. By establishing a method for the thermal simulation of very small scale heating elements, the goal of this study was to decrease the power consumption of PI micro-hotplates to a few milliwatts to make them suitable forvery low power applications. To this end, the mean heat transfer coefficients in air of the devices were extracted by finite element analysis combined with very precise thermographicmeasurements. A simulation model was implemented for these hotplates to investigate both the influence of their downscaling and the bulk micromachining of the polyimide substrate to lower their power consumptions. Simulations were in very good agreement with the experimental results. The main parameters influencing significantly the power consumption at such dimensions were identified and guidelines were defined allowing the design of very small (15 × 15 μm) and ultra-low power heating elements (6 mW at 300 ◦C). These very low power heating structures enable the realization of flexible sensors, such as gas, flow or wind sensors, for applications in autonomous wireless sensors networks or RFID applications and make them compatible with large-scale production on foil such as roll-to-roll or printing processes.

The monitoring of heat flux is becoming more and more critical for many technologies approaching nanometric dimensions. Scanning Thermal Microscopy (SThM) is one of the tools available for thermal measurement at the nanoscale. This measurement technics needs calibration samples. Therefore, micro-hotplates made of platinum heater suspended on thin silicon nitride (SiN) membranes were fabricated for the calibration of Scanning Thermal Microscopy probes. The objective is to obtain heated reference samples with localised resistive temperature sensors (RTD) on the membrane to probe the temperature on a micro-scale area (typically 10×10 μm2). This sensing area is dedicated to (1) quantify the thermal resistance between the SThM tip and hot surface contact; and to (2) evaluate the perturbation induced by the probe on the heat dissipation when the contact measurement is performed. In this communication, we report on the thermal design of low-power calibration chip and their fabrication, as well as the electro-thermal characterization of sensitive RTDs made using e-beam technology. Thermal contact measurements using a thermocouple based SThM probe validated the functionality of the calibration chip. © 2015 The Authors. Published by Elsevier Ltd.

The monitoring of heat flux is becoming more and more critical for many materials and structures approaching nanometric dimensions. Scanning Thermal Microscopy (SThM) is one of the tools available for thermal measurement at the nanoscale and requires calibration. Here we report on a micro-hotplate device made of a platinum heater suspended on thin silicon nitride (SiN) membranes integrating specific features for SThM calibration. These heated reference samples can include a localized resistive temperature sensors (RTD) or standalone platinum membranes (typically 10 × 10 μm2) on which the temperature can be measured precisely. This functional area is dedicated to (1) estimate the thermal resistance between the SThM tip and hot surface contact; and to (2) evaluate the perturbation induced by the probe on the heat dissipation when the contact measurement is performed. The thermal design of these low-power calibration chips, their fabrication, including sensitive RTDs patterned using e-beam technology, as well as their electro-thermal and electro-mechanical characterizations are presented. Robust operation of the chips up to 500 °C has been demonstrated with their membrane mechanically stable up to 250 °C and a low-power consumption of 16 mW at this operating temperature. The temperature mapping of the active areas was performed using two physical principles: local SThM temperature measurement using a thermocouple-based micro-probe and optical imaging using Near-Infrared (NIR) microscopy. Measurements coupling on one hand SThM probe and the integrated RTD and, on the other hand, SThM probe with optical imaging, validated the functionality of the calibration chips. The latter open new perspectives in the calibration of SThM probes.

Thermal characterizations at nano-scale remain a challenge since the emergence of nano-structured devices. Having advantages in term of lateral resolution compared to far field techniques, the scanning thermal microscopy has become an essential tool for local materials heat transport characterization. In the frame of the European Quantiheat Project, several laboratories have worked together trying to figure out and to obtain quantitative thermal measurements covering spatial scales from the micrometre to the nanometre.This document contains six chapters with four main parts, in which micro-wire thermocouple based SThM probes have been used to enhance our knowledge in quantitative thermometry at this scale. This kind of probe has been developed and improved for several years. We demonstrate that it is adapted for measuring temperature of active samples as well as thermal conductivity of passive samples.Through the dissertation, the last version of the microscope (hardware, software) and probe design are presented. Attached on a quartz tuning fork, the tip-sample contact force can be quantified. Placed in a vacuum chamber, this system permits a full control of predominant parameters on the measurement such as air pressure and contact force. Thanks to samples provided by Quantiheat partners, measurements in active and passive modes have been performed to demonstrate that quantitative measurements are feasible. By changing ambient conditions from primary vacuum to ambient pressure, the tip-sample heat transfer mechanisms have been analysed in detail to reveal the preponderant role of air and solid-solid contact conductions.; Les caractérisations thermiques à l'échelle nanométrique restent un défi depuis l'émergence de dispositifs nano structurés. Ayant des avantages en termes de résolution latérale par rapport aux techniques de champ lointain, la microscopie thermique à balayage est devenue un outil essentiel pour la caractérisation locale des propriétés thermiques des matériaux. Dans le cadre du projet européen « Quantiheat », plusieurs laboratoires ont travaillé ensemble pour essayer de comprendre et d'obtenir des mesures quantitatives couvrant les échelles spatiales allant du micro au nanomètre.Ce document contient six chapitres avec quatre parties principales, dans lesquelles des sondes SThM à thermocouples microfilaires ont été utilisées pour améliorer nos connaissances en thermométrie quantitative à cette échelle. Ce type de sonde a été développé et amélioré pendant plusieurs années. Nous démontrons qu'il est adapté pour mesurer la température d’échantillons actifs ainsi que la conductivité thermique d’échantillons passifs.Grâce à la thèse, la dernière version du microscope (matériel, logiciel) et la conception de la sonde sont présentés. Fixé sur un diapason en quartz, la force de contact pointe-échantillon peut être quantifiée. Placé dans une chambre à vide, ce système permet un contrôle complet des paramètres prédominants sur la mesure, tels que la pression de l'air et la force de contact. Les mesures en modes actif et passif ont pu être menées grâce aux échantillons fournis par les partenaires du projet « Quantiheat » afin de démontrer que des mesures quantitatives sont envisageables. En changeant les conditions ambiantes allant du vide primaire à la pression ambiante, les mécanismes de transfert de chaleur de l'échantillon-pointe ont été analysés en détail pour mettre en évidence le rôle prépondérant de l'air et des conductions de contact solide-solide.

Thermal characterizations at nano-scale remain a challenge since the emergence of nano-structured devices. Having advantages in term of lateral resolution compared to far field techniques, the scanning thermal microscopy has become an essential tool for local materials heat transport characterization. In the frame of the European Quantiheat Project, several laboratories have worked together trying to figure out and to obtain quantitative thermal measurements covering spatial scales from the micrometre to the nanometre.This document contains six chapters with four main parts, in which micro-wire thermocouple based SThM probes have been used to enhance our knowledge in quantitative thermometry at this scale. This kind of probe has been developed and improved for several years. We demonstrate that it is adapted for measuring temperature of active samples as well as thermal conductivity of passive samples.Through the dissertation, the last version of the microscope (hardware, software) and probe design are presented. Attached on a quartz tuning fork, the tip-sample contact force can be quantified. Placed in a vacuum chamber, this system permits a full control of predominant parameters on the measurement such as air pressure and contact force. Thanks to samples provided by Quantiheat partners, measurements in active and passive modes have been performed to demonstrate that quantitative measurements are feasible. By changing ambient conditions from primary vacuum to ambient pressure, the tip-sample heat transfer mechanisms have been analysed in detail to reveal the preponderant role of air and solid-solid contact conductions.; Les caractérisations thermiques à l'échelle nanométrique restent un défi depuis l'émergence de dispositifs nano structurés. Ayant des avantages en termes de résolution latérale par rapport aux techniques de champ lointain, la microscopie thermique à balayage est devenue un outil essentiel pour la caractérisation locale des propriétés thermiques des matériaux. Dans le cadre du projet européen « Quantiheat », plusieurs laboratoires ont travaillé ensemble pour essayer de comprendre et d'obtenir des mesures quantitatives couvrant les échelles spatiales allant du micro au nanomètre.Ce document contient six chapitres avec quatre parties principales, dans lesquelles des sondes SThM à thermocouples microfilaires ont été utilisées pour améliorer nos connaissances en thermométrie quantitative à cette échelle. Ce type de sonde a été développé et amélioré pendant plusieurs années. Nous démontrons qu'il est adapté pour mesurer la température d’échantillons actifs ainsi que la conductivité thermique d’échantillons passifs.Grâce à la thèse, la dernière version du microscope (matériel, logiciel) et la conception de la sonde sont présentés. Fixé sur un diapason en quartz, la force de contact pointe-échantillon peut être quantifiée. Placé dans une chambre à vide, ce système permet un contrôle complet des paramètres prédominants sur la mesure, tels que la pression de l'air et la force de contact. Les mesures en modes actif et passif ont pu être menées grâce aux échantillons fournis par les partenaires du projet « Quantiheat » afin de démontrer que des mesures quantitatives sont envisageables. En changeant les conditions ambiantes allant du vide primaire à la pression ambiante, les mécanismes de transfert de chaleur de l'échantillon-pointe ont été analysés en détail pour mettre en évidence le rôle prépondérant de l'air et des conductions de contact solide-solide.

Generation of short pulses with surface acoustic waves (SAW) is studied, in analogy with the principle of chirped pulse amplification (CPA) used to produce ultrashort laser pulses. Temporal compression of pulses is generally achieved with dispersive elements. A SAW transducer emitting short SAW pulses is used as a dispersive element in this work. A comparative study of chirped inter digital transducers (CIDTs) using the first order model and the p-matrix model is presented. SAW devices are designed and fabricated using the simulation results and the effect of the varying pitch of the CIDts on the response is studied. Appearance of band gaps due to internal reflections within the CIDts and its effect on the directionality of the CIDTs are in particular found and studied.A stabilized time-domain differential optical interferometer is then proposed in order to characterize short pulses, with the surface acoustic wave (SAW) sample placed outside the interferometer. Experiments are conducted with surface acoustic waves excited by a chirped inter-digital transducer on a piezoelectric lithium niobate substrate having an operational bandwidth covering the 200 MHz – 400 MHz frequency range and producing 10 ns pulses with 36 nm maximum out-of-plane displacement. The interferometric response is compared with a direct electrical measurement obtained with a receiving wide bandwidth inter-digital transducer and good correspondence is observed. The effects of varying the path difference of the interferometer and the measurement position on the surface are discussed. Pulse compression along the chirped inter-digital transducer is observed experimentally.Finally, a comparative study of different filter designs for generating short pulses is presented with an objective to find a design to produce the optimal pulse which is short in width and high in amplitude, for a given dispersive element. The inverse filter is found to be the most efficient as it produces a short pulse with the highest amplitude. To optimize the pulse compression for the fabricated devices, experiments are conducted to find the optimal trade-off curve for each chirp case.; La génération d’impulsions courtes d’ondes acoustiques de surface est étudiée, en s’inspirant du principe de l’amplification des impulsions chirpées qui est utilisée pour la génération d’impulsions laser ultrabrèves. La compression temporelle des impulsions est généralement réalisée à l’aide d’éléments dispersifs. Dans ce travail, un transducteur à ondes acoustiques de surface pouvant émettre des impulsions brèves est utilisé comme élément dispersif. Une étude comparative des transducteurs à peignes interdigités chirpés est menée avec un modèle du premier ordre et un modèle dit de matrice mixte. Des dispositifs à ondes acoustiques de surface sont conçus et réalisés à partir des résultats de simulation numérique. La façon de distribuer la période dans le transducteur est étudiée. L’apparition de bandes interdites dues aux réflexions internes dans le transducteur chirpé et son effet sur l’émission directionnelle des ondes surface sont en particulier observées et étudiées.Un interféromètre optique différentiel dans le domaine temporel et stabilisé est ensuite proposé afin de caractériser les impulsions brèves. Le transducteur à ondes acoustiques de surface est placé à l’extérieur de l’interféromètre. Des expériences sont conduites avec un transducteur à peignes interdigités chirpé ayant une bande opérationnelle couvrant la gamme de fréquences 200 MHz – 400 MHz et produisant des impulsions de 10 ns avec un déplacement hors-plan maximal de 36 nm. La réponse interférométrique est comparée à une mesure électrique directe obtenue à l’aide d’un transducteur de réception large bande ; une bonne correspondance des deux mesures est observée. Les influences de la différence de chemin optique dans l’interféromètre et du choix du point d’observation sur la surface sont discutées. La compression de l’impulsion le long du transducteur chirpé est observée expérimentalement.Finalement, une étude comparative de différents filtres de compression temporelle est présentée, dans l’objectif d’obtenir des impulsions optimales à la fois courtes temporellement et de forte intensité, pour un élément dispersif donné. Le filtre inverse est identifié comme le plus efficace et nous permet de produire les impulsions de plus grande amplitude. Afin d’optimiser la compression de l’impulsion pour les dispositifs fabriqués, des expériences sont conduites pour trouver les courbes de compromis optimal dans chaque cas de modulation de la période du transducteur.

Generation of short pulses with surface acoustic waves (SAW) is studied, in analogy with the principle of chirped pulse amplification (CPA) used to produce ultrashort laser pulses. Temporal compression of pulses is generally achieved with dispersive elements. A SAW transducer emitting short SAW pulses is used as a dispersive element in this work. A comparative study of chirped inter digital transducers (CIDTs) using the first order model and the p-matrix model is presented. SAW devices are designed and fabricated using the simulation results and the effect of the varying pitch of the CIDts on the response is studied. Appearance of band gaps due to internal reflections within the CIDts and its effect on the directionality of the CIDTs are in particular found and studied.A stabilized time-domain differential optical interferometer is then proposed in order to characterize short pulses, with the surface acoustic wave (SAW) sample placed outside the interferometer. Experiments are conducted with surface acoustic waves excited by a chirped inter-digital transducer on a piezoelectric lithium niobate substrate having an operational bandwidth covering the 200 MHz – 400 MHz frequency range and producing 10 ns pulses with 36 nm maximum out-of-plane displacement. The interferometric response is compared with a direct electrical measurement obtained with a receiving wide bandwidth inter-digital transducer and good correspondence is observed. The effects of varying the path difference of the interferometer and the measurement position on the surface are discussed. Pulse compression along the chirped inter-digital transducer is observed experimentally.Finally, a comparative study of different filter designs for generating short pulses is presented with an objective to find a design to produce the optimal pulse which is short in width and high in amplitude, for a given dispersive element. The inverse filter is found to be the most efficient as it produces a short pulse with the highest amplitude. To optimize the pulse compression for the fabricated devices, experiments are conducted to find the optimal trade-off curve for each chirp case.; La génération d’impulsions courtes d’ondes acoustiques de surface est étudiée, en s’inspirant du principe de l’amplification des impulsions chirpées qui est utilisée pour la génération d’impulsions laser ultrabrèves. La compression temporelle des impulsions est généralement réalisée à l’aide d’éléments dispersifs. Dans ce travail, un transducteur à ondes acoustiques de surface pouvant émettre des impulsions brèves est utilisé comme élément dispersif. Une étude comparative des transducteurs à peignes interdigités chirpés est menée avec un modèle du premier ordre et un modèle dit de matrice mixte. Des dispositifs à ondes acoustiques de surface sont conçus et réalisés à partir des résultats de simulation numérique. La façon de distribuer la période dans le transducteur est étudiée. L’apparition de bandes interdites dues aux réflexions internes dans le transducteur chirpé et son effet sur l’émission directionnelle des ondes surface sont en particulier observées et étudiées.Un interféromètre optique différentiel dans le domaine temporel et stabilisé est ensuite proposé afin de caractériser les impulsions brèves. Le transducteur à ondes acoustiques de surface est placé à l’extérieur de l’interféromètre. Des expériences sont conduites avec un transducteur à peignes interdigités chirpé ayant une bande opérationnelle couvrant la gamme de fréquences 200 MHz – 400 MHz et produisant des impulsions de 10 ns avec un déplacement hors-plan maximal de 36 nm. La réponse interférométrique est comparée à une mesure électrique directe obtenue à l’aide d’un transducteur de réception large bande ; une bonne correspondance des deux mesures est observée. Les influences de la différence de chemin optique dans l’interféromètre et du choix du point d’observation sur la surface sont discutées. La compression de l’impulsion le long du transducteur chirpé est observée expérimentalement.Finalement, une étude comparative de différents filtres de compression temporelle est présentée, dans l’objectif d’obtenir des impulsions optimales à la fois courtes temporellement et de forte intensité, pour un élément dispersif donné. Le filtre inverse est identifié comme le plus efficace et nous permet de produire les impulsions de plus grande amplitude. Afin d’optimiser la compression de l’impulsion pour les dispositifs fabriqués, des expériences sont conduites pour trouver les courbes de compromis optimal dans chaque cas de modulation de la période du transducteur.

This PhD thesis deals with the development of a thermalmicroscope using a local probe. This imagingsystem presents two functioning modes that allow determining either surface temperature or thermalproperties of materials. A micro-wire thermocouple is used as a thermal sensor. It is less invasiveand allows measuring the surface temperature with a large temperature range. Furthermore, themicroscope offers an advantage to be less sensitive to the optical nature of a sample surface thanoptical methods. To control the contact between the probe and the surface, a quartz tuning fork hasbeen used as a force sensor. An original excitation system has been developed based on the photothermaleffect. The microscope works also as a SThM since it permits to extract simultaneouslytopographical and thermal pictures (2 and 3 omega periodical modes). Results underlining themicro-thermocouple advantages, in terms of topographical compared to resistive probe techniquesfunctioning with the 3 omega method, have been obtained.; Ce mémoire de thèse s’inscrit dans le développement d’un microscope thermique à sonde locale.Ce système d’imagerie présente deux modes de fonctionnement permettant de déterminer soit unetempérature de surface soit des propriétés thermophysiques de matériaux. Un micro-thermocouplebifilaire a été utilisé comme capteur thermique. Il est peu invasif et permet d’accéder à destempératures de surface sur une large gamme de température. De plus, le microscope offrel’avantage d’être moins sensible à la nature optique des échantillons que les méthodes en champlointain. Dans le but de maitriser le contact entre la sonde et la surface, un résonateur à quartz(diapason) a été utilisé comme capteur de force. Un système d’excitation original basé sur l’effetphoto-thermo-élastique a été mis au point. Le microscope fonctionne donc comme un SThM puisqu’ilpermet d’extraire simultanément des images topographiques et thermiques (régime périodique 2 et3 oméga). En revanche, les résultats obtenus ont permis de mettre en évidence les avantages dumicro-thermocouple en termes de résolutions spatiales topographiques vis-à-vis des techniques àsondes résistives fonctionnant en mode 3 oméga.