David Alamarguy | Centre National de la Recherche Scientifique / French National Centre for Scientific Research (original) (raw)

Uploads

Papers by David Alamarguy

Sensors

YBa2Cu3O6+x (YBCO) cuprates are semiconductive when oxygen depleted (x < 0.5). They can be use... more YBa2Cu3O6+x (YBCO) cuprates are semiconductive when oxygen depleted (x < 0.5). They can be used for uncooled thermal detection in the near-infrared: (i) low temperature deposition on silicon substrates, leading to an amorphous phase (a-YBCO); (ii) pyroelectric properties exploited in thermal detectors offering both low noise and fast response above 1 MHz. However, a-YBCO films exhibit a small direct current (DC) electrical conductivity, with strong non-linearity of current–voltage plots. Calcium doping is well known for improving the transport properties of oxygen-rich YBCO films (x > 0.7). In this paper, we consider the performances of pyroelectric detectors made from calcium-doped (10 at. %) and undoped a-YBCO films. First, the surface microstructure, composition, and DC electrical properties of a-Y0.9Ca0.1Ba2Cu3O6+x films were investigated; then devices were tested at 850 nm wavelength and results were analyzed with an analytical model. A lower DC conductivity was measured ...

LGEP 2013 ID = 1454International audienc

HAL (Le Centre pour la Communication Scientifique Directe), Jun 23, 2021

Microelectronic Engineering, 2018

Journal of Nano Research, 2020

A complex ZnO/ZnAl2O4 heterostructures thin films on glass and Si (111) substrates have been succ... more A complex ZnO/ZnAl2O4 heterostructures thin films on glass and Si (111) substrates have been successively obtained by a soft ultrasonic spray pyrolysis (USP) method deposition using the Zn/Al molar ratios concentrations of 0.07/0.13 and 0.1/0.1, respectively. According to (XRD) an ordered zinc oxide (ZnO) and zinc aluminate (ZnAl2O4) structures deposited onto glass from the air annealing at 500 °C during 2 hours was observed and confirmed by the (EDX), (FTIR) and Raman spectroscopy techniques. The estimated crystallites size and stress values of ZnO and ZnAl2O4 in the ZnO/ZnAl2O4/glass film were 19 nm/0.469 GPa and 11 nm/-0.292 GPa, respectively. The lower Zn/Al molar ratio around 0.035/0.06 produced only ZnO as a single phase, suggesting the Al insufficient quantity. The Si (100) substrate with 0.07 Zn molarity conducted to the Zn2SiO4/ZnO/ZnAl2O4 composite. The Raman integrated intensity bands of ZnO and ZnAl2O4 increases with increasing Zn to Al molar ratio (0.1/0.1 comparatively...

Thin Solid Films, 2016

YBa2Cu3O6+x (YBCO) cuprates are semiconducting when oxygen depleted (x < 0.5). We have deposit... more YBa2Cu3O6+x (YBCO) cuprates are semiconducting when oxygen depleted (x < 0.5). We have deposited, by DC sputtering at 150 °C, amorphous YBCO (a-YBCO) semiconducting films to evaluate their potential as sensing layer for thermal detection of infrared (IR) radiation. Low temperature elaboration is a key advantage to integrate a radiation detector on a silicon chip bearing already processed readout electronics. We have studied an a-YBCO/metal planar structure test vehicle in the near-IR, concentrating on the high-pass pyroelectric response observed for the device. This response exhibited interesting features: i) because originating from a capacitance current signal, no DC bias was required, hence a low noise current level; ii) the high-pass pyroelectric cutoff was observed in the 20 to 40 kHz modulation frequency range; iii) the low-pass cutoff, of readout circuitry origin, was pushed towards the MHz range, with a time constant of ~ 2 μs. The use of an analytical model allowed to simulate correctly the device amplitude and phase of the response as a function of the modulation frequency. All the model parameters were introduced, without adjustment, according to the actual geometrical, physical and electrical characteristics of the device and its measurement setup. The low noise and fast response was characterized by a detectivity above 109 cm·Hz1/2·W− 1, in the 500 Hz to 100 kHz range; these features are very promising for fast imaging applications. Migration from near-IR towards mid- and far-IR is also considered.

2009 Proceedings of the 55th IEEE Holm Conference on Electrical Contacts, 2009

Many connectors are made of cuprous substrates with electroplated final surfaces. When failure of... more Many connectors are made of cuprous substrates with electroplated final surfaces. When failure of the devices occurs, fretting and intermetallic compound formation are very often involved. This paper describes the influence of different types of underlayers on tin intermetallic compound formation. The physical and chemical properties of the intermetallic compounds are described: various techniques are used to characterise their topography, structure and composition. These include: AFM, XPS, SEM, EDX. Glow discharge optical emission spectroscopy (GD-OES) is also used for quantitative depth profiling of the samples. A stripping method is used in order to evaluate the tribological and electrical properties of the intermetallic layers, independently of the tin particle formation occurring with tin layers. The analysis of the results is based on the various values of size and morphology of the grains. Very particular features are observed in the case of thin underlayers of cobalt, as the diffusion of copper into the tin layer seems to be minimised. The electrical and tribological properties of ball on plane contacts of tinned cuprous substrates with such underlayers are observed to be fairly stable even after periods of thermal heating. Keywords-components; tin intermetallic compound, diffusion, fretting, contact resistance.

Proceedings of the Forth-Seventh IEEE Holm Conference on Electrical Contacts (IEEE Cat. No.01CH37192)

Degradation phenomena occurring during the lifetime of tinned separable electrical contacts remai... more Degradation phenomena occurring during the lifetime of tinned separable electrical contacts remain a factor of loss of reliability that can be minimised. In a previous paper, friction, wear and electrical properties of hot-dipped tin coatings on bronze substrates have been analysed with various techniques in order to show the improvement due to a well-suited fluorinated lubricant layer. Contacts were of the sphere on plane type obtained from strips of tinned CuSn/sub 4/ (as received for the flats, and formed by stamping for the dimples). Macroscopic friction cycles simulating insertion and withdrawal of separable contacts were performed as well as fretting cycles. Efficiency of the lubricant was strongly related to the film thickness in the case of macroscopic friction of dimple on flat contacts. For a sufficient film thickness, different behaviours were observed for different molecules. Here, the particularity of lubrication mechanisms of hot-dipped tin contacts is analysed. The evolution of static contact resistance values before friction and during the friction tests correlated to the wear behaviour shows the influence of some of the lubricant properties such as viscosity and chain structure.

2012 IEEE 58th Holm Conference on Electrical Contacts (Holm), 2012

Corrosion of gold coated electrical contacts remains a problem often avoided by keeping the final... more Corrosion of gold coated electrical contacts remains a problem often avoided by keeping the final gold coating thicknesses over 1 μm. Graphene has recently been shown to be an outstanding material: among its astonishing properties are the theoretical carrier mobility at room temperature (200 000 cm2/V-1s-1) and the Young modulus (1.5 TPa). Graphene is a one-atom thick two-dimensional carbon crystal and has been first produced by mechanical exfoliation to obtain high purity defect free sheets. Chemical vapour deposition (CVD) is another method producing larger areas of graphene. Much work has been dedicated to graphene oxide (GO) deposition and reduction processes for applications ranging from electronics to sensors. In this work we describe briefly how a method of liquid exfoliation and spray deposition can be used to produce nanometric films of graphene flakes which can be more or less uniform and continuous according to the tuning of the process. Films were sprayed in different conditions on various substrates: laboratory substrates such as evaporated gold on glass, Si wafers and metallic coupons. The coupons under study were cut from cuprous alloy strips with a 2μm Ni underlayer and a 0.8 μm Au layer. The coupons were coated with graphene films; they were then submitted to a four gas corrosion environmental test of the GR-1217-CORE Nov. 1995 type. A significant protection effect was observed for the sprayed graphene films. The deposition method by means of a spraying device was difficult to characterise but Raman spectroscopy and SEM images of the sprayed films showed evidence of the film formation. Contact resistance measurements and friction tests in a ball plane configuration were performed; low values of resistance and very low friction coefficients were measured. These first results show the very strong potential of graphene films deposited by a spraying method for electrical contacts applications and particularly for corrosion protection.

2010 Proceedings of the 56th IEEE Holm Conference on Electrical Contacts, 2010

The areas of nanoscience and nanoengineering have been developing very fast; a large range of nan... more The areas of nanoscience and nanoengineering have been developing very fast; a large range of nanoscale materials has been studied in view of various practical applications. Much work is performed in the area of innovating coatings. Such films require specific properties such as proper conduction and mechanical ones. These properties can be studied by conductive probe AFM (CP-AFM) techniques. These