TRAMP addresses the scientific and technical details of the origin and potential use of the giant piezoresponse observed in silicon nano-objects. After a 10 year debate about the veracity of the giant piezoresistance (PZR) in silicon nanowires, the TRAMP partners (all of whom have been visible participants in this debate) have preliminary evidence for a giant piezocapacitive (PZC) effect. Experiments suggest a central role for stress-induced changes to the charge state of intrinsic defects at the silicon/oxide interface (specifically the Pb0 defect). The capacitive (rather than resistive) nature of the phenomenon is a surprise and the TRAMP partners have the opportunity to be ‘first-in-field’, both in terms of the fundamental science, but also for device applications of this novel phenomenon that occurs in scalable, top-down fabricated silicon nano-objects. In the initial phase of the project, the TRAMP partners will fabricate ohmically contacted, top-down silicon nanomembranes to be tested in a taylor-made apparatus that allows for the frequency and voltage dependence of the piezoresponse to be measured under uniaxial tensile and compressive stresses up to ˜150 MPa. The dependence of the piezoresponse on doping, temperature and nano-object geometry will be explored and then used to improve the design of a second process batch. This method of rapid prototyping has been used previously by the TRAMP partners, and will yield a map of the relative importance of the PZR and PZC responses as a function of these parameters. This is not only essential from the point of view of developing a microscopic understanding of the phenomenon, but also in terms of optimizing conditions for its use as a stress or motion transduction mechanism. Proper characterization of the piezoresponse will employ two techniques specifically adapted to nano-objects: micro-Raman spectroscopy for the measurement of the local stress in nano-objects, with the option to use TERS for the smallest objects, and Laplace current transient spectroscopy for the identification of the electromechanically active defects thought to be responsible for the giant, anomalous piezoresponse. This latter method is not yet widely used but is adapted to defect spectroscopy on any electrically connected nano-objects whose capacitance is too small to permit the use of more traditional capacitive spectroscopies. Once the optimal conditions (i.e. for maximum, stable PZC) have been determined, the TRAMP partners will undertake a technical study of two potential applications: the electrical detection of process induced microstrains in the active layer of ultra-thin commercial silicon-on-insulator wafers for quality control purposes; and as a means to detect motion in a nano-mechanical resonator where standard optical or capacitive methods lose sensitivity. The second application requires the fabrication of in-plane nanoresonators in which the TRAMP partners are expert. In the final task of the project the results of these two technical studies will be used as the basis for discussions with potential industrial partners. Impacts of a successful TRAMP project will therefore include high visible scientific and technical results, the first steps in the characterization of devices exploiting the PZC that are based on a scalable, top-down silicon technology, the patenting of intellectual property, and exploratory talks with partners from the semiconductor manufacturing industry aimed at licensing or collaborative opportunities.

GaNGUN The project aims to achieve a THz oscillator based on Self-Switching Diodes (SSD) in gallium nitride. SSD devices (GaN based) have been shown to have to capability to produce current oscillations at 300 GHz, under specific conditions and topologies (strong polarization). Based on technological SSD results already obtained within consortium, up to 325 GHz for THz detectors, GaNGUN proposes new epitaxial structures, new topologies and integration into a guiding structure to achieve this THz oscillator. To achieve this goal, simulation skills, materials growth, technological processes and characterization have been merged in this international project.

The CASSIOPES project has two main goals. On the one hand, the first purpose of this project is to fabricate a functional 3D Li-ion all solid state micro-battery by using thin film technologies allowing to reach high energy density (> 5 mW.cm-2). 3D Lithium ion technology is proposed in order to find a suitable alternative to commercially available planar metallic lithium micro-battery. To fabricate the 3D prototype, Atomic Layer Deposition facility has been selected as the thin film deposition tool. On the other hand, all the thin films within the micro-battery (electrodes, electrolyte, current collectors, seed layer…) will be studied in order to investigate and to understand the charge storage mechanism in a dynamic way during cycling by using advanced in situ/operando characterization technique available within the consortium. The energy density of the 3D Li-ion micro-battery technology proposed in the frame of the CASSIOPES project will be 5 up to 10 times higher than the planar technology. Moreover, CASSIOPES aims at breaking technological barriers as proposed as strategic direction by the SNR (instrumentation, in situ/operando characterization, study of interface at the nanoscale – 15th orientation). The in situ/operando characterization tool developed within CASSIOPES project has already used in bulk electrodes or batteries but should be revised in order to match with the problematic of thin films technology for electrochemical energy storage. Those techniques has been listed as priority activity of the “Defi 3 – axe4”.

Contamination of surfaces of food processing lines by pathogens and spoilage bacteria is a major issue that has not yet found a proper cleaning and disinfection solution. Indeed, after hygienic procedures, adherent bacteria are still commonly found on surfaces, mostly in the form of adherent spores, e.g. Bacillus spores in closed equipment or in the form of biofilms, e.g. those partially composed of Pseudomonas spp. These adherent bacteria are known to be responsible for many food- poisoning, thus underlining the needs for implementing more efficient procedures associated with a better understanding of the underlying mechanisms. Thanks to an ongoing collaboration, it has been recently shown by the partners that the drying conditions play a major role on the persistence of surface contamination. The goal of the proposed research is to bring researchers with complementary skills, the opportunity to work on this specific problem that begs a concrete technological solution. The project focuses on key research ideas of combined biology, fluid mechanics and advanced metrology (i) to improve the comprehension of bacterial adhesion in complex industrial environments and (ii) to propose optimal hydrodynamic solutions (based on interfacial flows) to remove adherent bacteria (bacterial spores used as a model) in industrial equipment without overuse of chemical products. The approach will consist of (a) characterizing the dynamical evolution of spore adhesion forces during drying/wetting cycles in their complex environment and unveiling the origin of these forces and (b) determining the optimal two-phase flow configurations capable of efficiently removing spores. The issue (a) will be tackled through precise real-time monitoring of (i) the evolution of spore adhesion forces during wetting/drying cycles with micropipettes and microfluidic based systems and (ii) the kinetics of interaction between spores and substrates in connection with their respective wetting properties thanks to the observation of interfaces by confocal and electron microscopy, the observation under optical microscope of the spore detachment in flow cells and the development of dedicated acoustical sensors. In the part (b), the numerical (Boundary Integral Method) and experimental (at microscopic and pilot scales) tools will allow the determination of optimal two-phase flows capable of detaching any adherent bacteria from various materials. Such flows would prevent the unnecessary overuse of chemicals for equipment disinfection and, therefore, contribute to the implementation of greener industrial processes. Intellectual Impacts: The multidisciplinary consortium includes international collaborators and the synergies are fully complementary. The partnership will advance sciences on multiphase fluid and bacterial contamination of surfaces, with several technological applications including bio-sensors, multiphase flow cleaning processes and control of equipment hygiene for a multitude of industries related to agriculture, pharmaceuticals, metallurgy and energy. Some key science issues associated with bacteria adhesion to food production lines and instabilities in multiphase flows will be resolved. The proposed collaboration would promote further partnerships between industry and academe. Broader Impacts: The project will enhance the training of young scientists in cutting edge international research settings. Dissemination will be achieved by journal publications, webinars and web sites. Transfer of Knowledge: The combined expertise of international institutes will result in transfer of knowledge via site visits and workshops. It will include the numerical and analytical methods as well as the experimental techniques associated with microfluidics and microbiology. The transfer of knowledge will take place in both directions and will become the permanent foundation for sustained collaboration.

Layered heterostructures integrating two-dimensional materials such as graphene or transition metal dichalcogenides and nanometer-scale layers of inorganic materials are attracting considerable attention since a few years. Organic materials remain however poorly explored in this context, in particular for ultra-thin layers down to the single molecule level. Mixed-dimensional, hybrid heterostructures have a lot to offer in terms of interface physics in fields such as, for instance, polaritonics, excitonics or topological phases and provide new emergent behavior for electronics and optoelectronics. In this context, vertical organic transistors are promising to outperform the usual performance indicators of horizontal organic thin-film transistors such as transconductance, cut-off frequency and high integration. Up to now, research on this type of devices has mostly focused on vertical organic field-effect transistors. Another type of transistor, the vertical permeable base transistor remains however poorly studied although graphene, as a semi-premeable membrane for electrons, could offer here an exceptional control. Our main goal with this project is to provide a better fundamental understanding of the interface in hybrid, mixed-dimensional Van der Waals heterostructures with high electronic bandwidth. We will design, fabricate and study vertical heterostructures in the form of organic/graphene/organic stacks and the quality of the organic/graphene interface will be investigated to optimize charge injection through the graphene base. Extensive electrical characterization, from dc up to THz frequencies, and ab-initio simulations will be performed to achieve a deep understanding of these systems. The hybrid design of the proposed structures combining organic materials (organic semiconductors, graphene), metallic contacts and, ultimately, flexible substrates bear a strong potential for application in flexible electronics using the concept of vertical, permeable-base transistor. The project in organized in three scientific workpackages. (1) We will first focus on the assembly of small molecules and polymer semiconductors with a graphene layer on a substrate. We will characterize the structural and basic electronic properties of this vertical graphene/organic semiconductor interface. (2) A detailed electrical characterization (DC + AC) will then give us access to the physics of this interface and to essential electrical parameters such as the charge transfer between the layers and charge carriers mobility, graphene doping and tunable barrier height parameters. (3) Finally, we will investigate, as a proof of concept, the electronic properties of graphene permeable-base vertical organic transistors.