Pulsed laser writing of graphitic electrodes in diamond is a promising technique for innovative particle detectors. Although of great relevance in 3D fabrication, the processes involved in ...sub-bandgap bulk irradiation are still not well understood. In this work, Raman imaging is exploited to correlate resistivity and graphitic content in 5–10 μm-thick electrodes, obtained both in the domains of femtoseconds and of nanoseconds of pulse duration. A wide interval of resistivities (60–900mΩcm), according to the irradiation technique employed, are correlated with an sp2 content of the modified material ranging over a factor 2.5. The stress distribution (maximum of about 10GPa) and the presence of nanostructured sp3 material around the graphitic columns have also been studied by Raman spectroscopy, and a rationale for the conductive behavior of the material is presented in terms of the thermodynamics of the process.
•Fabrication of superficial and buried graphitic structures in diamond by means of ns- and fs-pulsed laser radiation•Quantitative 2-dimensional maps of the phase composition and of the stress conditions were obtained by micro-Raman imaging.•A correlation between electrical conductivity and graphitic content was assessed.•A rationale for the different composition of phases obtained in different condition has been found.
Electrical properties of laser-bonded Silicon-On-Diamond samples Sciortino, S.; Brandi, F.; Carzino, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Letnik:
730
Journal Article
Recenzirano
In this work we report preliminary tests aimed at the implementation of a Silicon-On-Diamond (SOD) radiation sensor. SOD materials have been prepared by continuously scanning a 20ps pulsed 355nm ...laser beam on the silicon–diamond interface. A pixel monolithic sensor has also been bonded to diamond with the same technique and tested to show that a complex electronic chip can undergo the process without any damage. Through silicon vias have been fabricated by laser drilling on the silicon side of the SOD samples and their insulation from the silicon bulk has been tested. The charge collection efficiency of a diamond sensor with laser-written graphitic contacts has been measured, to demonstrate a reliable and simple way to fabricate ohmic contacts on the diamond side of the SOD devices. Finally, a SOD material with electric contacts on the silicon and on the diamond sides has been tested as a particle sensor to demonstrate the electrical continuity of the silicon–diamond interface after the bonding.
•The steps necessary to fabricate a monolithic Silicon-On-Diamond detector have been carried out.•These steps involve the bonding, by a laser technique, of an electronic chip on diamond without damage, the growth of insulated Through Silicon Vias in silicon, the fabrication of ohmic contacts by laser graphitization.•In conclusion: the feasibility of a SOD detector with the readout silicon electronics bonded to the diamond sensitive volume has been demonstrated.•Graphitic contacts compare favorably with standard metallic ones.•Charge is collected by a SOD material. That is, the silicon–diamond bonding interface does not prevent charge collection.
Micro-fabrication in diamond is applicable in a wide set of emerging technologies, exploiting the exceptional characteristics of diamond for application in bio-physics, photonics and radiation ...detection. Micro ion-beam irradiation and pulsed laser irradiation are complementary techniques, which permit the implementation of complex geometries, by modification and functionalization of surface and/or bulk material, modifying the optical, electrical and mechanical characteristics of the material. In this article we summarize the work done in Florence (Italy), concerning ion beam and pulsed laser beam micro-fabrication in diamond.
A new method of preparation of silicon-on-diamond materials is discussed in detail. Pre-characterization of the samples surfaces has been carried out, in order to calculate the optimal pressure for ...surface contact before the bonding process. The method is based on pulsed laser irradiation, in the 20
ps–7
ns range, at a wavelength of 355
nm, for which diamond is transparent and silicon highly absorbing. Under these conditions the material melts locally, within 100
nm at the interface, giving rise to amorphous silicon and silicon carbide. The mechanical strength of the bonding has been assessed by adhesion tests. Preliminary result on resistance to thermal annealing at 400
C in air is also reported. Uniformity of the silicon–diamond interface has been verified by scanning electron microscopy. Raman and infrared spectroscopy allowed to detect and estimate quantitatively the amorphous Si and SiC phases at the interface. A finite element simulation has been carried out, taking into account the processes occurring during the laser pulse and the subsequent cooling of the materials. As a result, energy densities per pulse required to melt locally diamond and silicon have been obtained as functions of the pulse width, giving a rationale to the formation of the SiC bond in terms of diamond–silicon inter diffusion. The experimental results of bondings performed at various energy density and pulse widths are in agreement with the model. The experimental results and the theoretical predictions are compared and discussed.
In response to the need for a sophisticated powered upper-limb orthosis for use by people with disabilities and/or limb weakness or injury, the MULOS (motorized upper-limb orthotic system) has been ...developed. This is a five-degree-of-freedom electrically powered device having three degrees of freedom at the shoulder, one at the elbow and one to provide pronation/supination. The shoulder mechanism consists of a serial linkage having an equivalent centre of rotation close to that of the anatomical shoulder; this is a self-contained module in which power transmission is provided by tensioned cables. The elbow and pronation/supination modules are also self-contained. The system has been designed to operate under three modes of control: 1. As an assistive robot attached directly to the arm to provide controlled movements for people with severe disability. In this case, it can be operated by a variety of control interfaces, including a specially designed five-degree-of-freedom joystick. 2. Continuous passive motion for the therapy of joints after injury. The trajectory of the joints is selected by 'walk-through' programming and can be replayed for a given number of cycles at a chosen speed. 3. As an exercise device to provide strengthening exercises for elderly people or those recovering from injury or surgery. This mode has not been fully implemented at this stage. In assistive mode, prototype testing has demonstrated that the system can provide the movements required for a range of simple tasks and, in continuous passive motion (CPM) mode, the programming system has been successfully implemented. Great attention has been paid to all aspects of safety. Future work is required to identify problems of operation, and to develop new control interfaces.
First result on biased CMOS MAPs-on-diamond devices Kanxheri, K.; Citroni, M.; Fanetti, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2015, Letnik:
796
Journal Article
Recenzirano
Recently a new type of device, the MAPS-on-diamond, obtained bonding a thinned to 25μm CMOS Monolithic Active Pixel Sensor to a standard 500μm pCVD diamond substrate, has been proposed and ...fabricated, allowing a highly segmented readout (10×10μm pixel size) of the signal produced in the diamond substrate. The bonding between the two materials has been obtained using a new laser technique to deliver the needed energy at the interface. A biasing scheme has been adopted to polarize the diamond substrate to allow the charge transport inside the diamond without disrupting the functionalities of the CMOS Monolithic Active Pixel Sensor.
The main concept of this class of devices is the capability of the charges generated in the diamond by ionizing radiation to cross the silicon–diamond interface and to be collected by the MAPS photodiodes. In this work we demonstrate that such passage occurs and measure its overall efficiency. This study has been carried out first calibrating the CMOS MAPS with monochromatic X-rays, and then testing the device with charged particles (electrons) either with and without biasing the diamond substrate, to compare the amount of signal collected.
Silicon frontend electronics and high particle rates at LHC Buffini, A.; Busoni, S.; Meschini, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2001, Letnik:
461, Številka:
1
Journal Article
Recenzirano
In this work, we have exploited the possibility of swapping the functionalities of the two stages of fast frontend electronics based on the usual preamplifier and shaper structure. Measurements on a ...prototype of the CMS frontend chip (APV6) confirm what expected from general considerations: invariance of the output shape and amplitude, and tolerance to very high particle rates. The noise may increase marginally because of the different impedance of the first stage, which depends on the peaking time.
The RD48 (ROSE) collaboration has succeeded to develop radiation hard silicon detectors, capable to withstand the harsh hadron fluences in the tracking areas of LHC experiments. In order to reach ...this objective, a defect engineering technique was employed resulting in the development of Oxygen enriched FZ silicon (DOFZ), ensuring the necessary O-enrichment of about 2×10
17 O/cm
3 in the normal detector processing. Systematic investigations have been carried out on various standard and oxygenated silicon diodes with neutron, proton and pion irradiation up to a fluence of 5×10
14
cm
−2 (1
MeV neutron equivalent). Major focus is on the changes of the effective doping concentration (depletion voltage). Other aspects (reverse current, charge collection) are covered too and the appreciable benefits obtained with DOFZ silicon in radiation tolerance for charged hadrons are outlined. The results are reliably described by the “Hamburg model”: its application to LHC experimental conditions is shown, demonstrating the superiority of the defect engineered silicon. Microscopic aspects of damage effects are also discussed, including differences due to charged and neutral hadron irradiation.
Diamond pixel modules Asner, D.; Barbero, M.; Bellini, V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2011, Letnik:
636, Številka:
1
Journal Article
Recenzirano
With the commissioning of the LHC in 2010 and upgrades expected in 2015, ATLAS and CMS are planning to upgrade their innermost tracking layers with radiation hard technologies. Chemical Vapor ...Deposition diamond has been used extensively in beam conditions monitors as the innermost detectors in the highest radiation areas of BaBar, Belle, CDF and all LHC experiments. This material is now being considered as a sensor material for use very close to the interaction region where the most extreme radiation conditions exist. Recently the RD42 collaboration constructed, irradiated and tested polycrystalline and single-crystal chemical vapor deposition diamond sensors to the highest fluences expected at the super-LHC. We present beam test results of chemical vapor deposition diamond up to fluences of 1.8×10
16
protons/cm
2 illustrating that both polycrystalline and single-crystal chemical vapor deposition diamonds follow a single damage curve. We also present beam test results of irradiated complete diamond pixel modules.
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