Ion impact on surfaces can induce surface modifications on the nano-scale. Different types of topological modifications are possible, like hillocks and craters, but in most cases, hillocks have been observed. These modifications can be produced by different types of ions. Ions deposit energy mainly by their potential energy (charge state) or kinetic energy (velocity). Slow highly charged ions (HCI), due to capture processes in front of the surface, as well as swift heavy ions (SHI), due to ionization processes inside the target, disturb the electronic system of the target heavily. A first indicator for this interpretation is the fact that the surface damage process usually has a threshold, either in the charge state (HCI) or the kinetic energy (SHI). Understanding, comparing and adapting the effects of different ion species for targeted surface modifications is the goal of the proposed project. Besides their excitation of the electronic system, slow and fast ions induce their main damage in different locations: slow HCI produce predominantly surface damage, whereas SHI do their damage mainly in the bulk (ion track). In order to compare the two ion types more easily, we will concentrate on grazing incidence with SHI. This particular collision geometry forces the track to a region close to the surface, comparable with the shallow damage of slow HCI. So far studies were done with individual combinations of irradiation parameters, like ion type, charge state and velocity, as well as target type and structure. We plan to concentrate on a relatively limited number of targets, but to study them in detail with a large number of ion types. We will start with three materials, whose reaction to ion beams is partially known, i.e. SrTiO3, TiO2 and CaF2. Depending on the obtained results, we will expand this initial choice to other types of materials. Until now, the main tools for the study of surface modifications were near-field methods. In most cases, atomic force microscopy (AFM) was used, therefore studying the topology of the modifications. We propose to use other methods, like high-resolution transmission electron microscopy, to also study the structure of the damage, and especially its extent into the volume, and not only the surface shape. We will also perform chemical and structural investigations of the perturbed regions using surface characterization techniques such as XPS, Auger, LEED and RBS/channeling. These studies will be combined with tools with sufficiently high spatial resolutions, like AFM and MET, to examine the effect of individual ion impacts. This broad variety of techniques will allow us to explore the damaging processes, and can lead to a better understanding of the mechanisms involved, which may ultimately lead to the application of these specific ions in surface nano-engineering. The choice of the partners is straightforward: the Vienna group is expert on surface characterization in particular with AFM, and has especially done ground-breaking work on interactions with slow, extremely highly charged ions with surfaces; whereas the Caen group has due to the GANIL facility, a large range of ions at their disposal, from eV to GeV kinetic energy. The French group is specialist on TEM measurements, and has done ground-breaking work on grazing angle incidence with swift heavy ions. The project will be the subject of a doctoral thesis on the Vienna side as well as a study by a post-doctoral fellow on the Caen side. Results will be disseminated on conferences and in international, peer reviewed publications.

There is now a true international economic competition to develop strategic and socio-economic solutions to manage our energy independence as well as our production of greenhouse gas emissions. One of them concerns the production of future low cost solar cells having high conversion efficiency, with the objective of achieving production costs below € 0.5/W by 2030 in Europe. It is in this context that the GENESE project proposes an original approach to allow the conversion of light using a combination of Atomic scale Si sensitizers and/or Ag nanoparticles and rare earth ions coupled to a nanostructuration of the substrate. The objectives are (i) to determine the feasibility of such structures for frequency conversion, and (ii) to identify the most promising structure for sensor such that it benefits from a high absorption cross section and an engineering of the spectral absorption. Such sensors offer a high potential for economic development since the different pathways studied in this project are compatible with the photovoltaic industry.

The NIOBIUM project aims at the first realization of a metal-base transistor (MBT) in the III-N semiconductor family. The key point is to develop by epitaxy an original crystalline III-N/metal/III-N heterostructure. The core of the project is the elaboration by molecular beam epitaxy (MBE) of Niobium nitride thin films, the proposed material for the metal base layer. This new generation of high-frequency vertical devices would represent a remarkable breakthrough in the field of GaN radio frequency (RF) devices and would play a major role in the growing demand for connectivity. This breakthrough will be all the more significant as the NIOBIUM project proposes to realize these new MBT devices on silicon substrates. High electron mobility transistors (HEMTs) on GaN have been studied for more than 20 years. However, their lateral geometry makes it more and more difficult to increase their operation frequency. Vertical transistors overcome several limitations of HEMTs. The reduction of lateral dimensions at high frequency is less drastic, and the device is less sensitive to surface effects. Although good crystal quality NbN/III-N and III-N/NbN heterostructures have been published in the last few years, most of them obtained by MBE, no III-N/NbN/III-N heterostructure realized by epitaxy has been published to date. The originality of the project lies mainly in the complementary expertise of III-V Lab, CRHEA and CIMAP. III-V Lab, an industrial research laboratory, has a long history and great expertise in the field of semiconductor components. III-V Lab has recently obtained a patent on metal-based transistors in the III-N semiconductor family. CRHEA brings more than 25 years of expertise in the field of epitaxy of III-N materials. Thanks to the specific know-how of the CRHEA in the epitaxy of III-N on silicon, the growth of NbN containing heterostructures will be optimized on this substrate. The ultimate control of the heterostructures necessary for the demonstration of an MBT transistor will be made possible by a close collaboration with CIMAP, which has the latest technologies and a remarkable expertise in the field of transmission electron microscopy (TEM). The GaN radio frequency (RF) market is growing rapidly from 630Mn€ in 2019 to 1.7Md€ in 2025 and this seems likely to continue with the arrival of 5G and then 6G. By proposing an innovative transistor with a vertical geometry that allows to reach higher frequencies, while circumventing the locks that limit the performance of HEMTs, the NIOBIUM project offers an opportunity to achieve a remarkable breakthrough in the field of very high frequency components, a strategic area for the technological sovereignty of France and Europe. Finally, the elaboration by epitaxy of original III-N/NbN heterostructures with an ultimate control of interfaces and thicknesses, where the NbN layer will be metallic at room temperature and superconducting at low temperature, will undoubtedly allow breakthroughs in many other fields where the quality of this type of metal/semiconductor and superconductor/semiconductor heterojunctions plays a key role. Examples include the study of disorder in the superconducting properties of NbN thin films with applications in the fabrication of high-performance single photon detectors, or the excitation of acoustic waves at the metal/semiconductor piezoelectric interface with applications in the fabrication of bulk acoustic wave resonators. The development of GaN-based RF components is part of the III-V Lab (Thales-Nokia-CEA-LETI GIE) strategy. Moreover, the links of III-V Lab with UMS (Thales-Airbus JV) allow easier industrial transfers.

Few-cycle or single optical cycle pulse duration, carrier–envelope phase (CEP) control, high pulse energy are several signature requirements to laser sources dictated by modern high-intensity physics. The advent of the technique of chirped pulse amplification (CPA) 25 years ago and the invention of Ti:sapphire ensured a steady pulse intensity increase around the wavelength of 800 nm. However, the average power of the most advanced Ti:sapphire sources is limited to about 20 W, roughly defining the current state of the art as 1 TW peak power at a 1-kHz repetition rate. The goal of this project is to achieve a radical breakthrough in the average power and energy scalability of 5-100-kHz (multi)mJ femtosecond sources while ensuring wavelength tunability, CEP stability and the few-cycle pulse duration. Although Yb-doped materials are well suited for average power scaling because of the low parasitic heat excreted by the optical pump on the laser crystal, no broadband Yb amplifiers exist to date that could generate femtosecond pulses at the energy level higher than just a few mJ at a kHz repetition rate as a result of the low brightness of pump laser diodes and shortcomings of heat transport from the amplifier crystal. In this project, the 4 partners bring together their complementary proprietary knowhow that provides a perfect combination to resolve the multi tens kHz amplifier scalability challenge. The enabling pioneering concept contributed by CELIA to this project is a scalable fiber pump laser with an excellent beam quality and the concept of high-brightness pumping of long Yb materials with these fiber pump sources. The project will consists in the development of a high average power fiber pump laser around 976 nm, a controlled growth technique of long Yb-doped crystals and new laser architectures adapted to these crystals. The CIMAP laboratory is a expert in Yb-doped single crystal growth. The Laboratoire Charles Fabry de l’Institut d’Optique (LCF) works on diode pump femtosecond oscillators and amplifiers since many years. The startup compny Azur Light Systems will bring his industrial expertise to create an all fibered prototype pump laser. Finally, CELIA has become an expert in the design of innovative fibers (Rod type fibers and Bragg fibers) and develop since its beginning high energy femtosecond systems at high and ultrahigh repetition rates. CELIA has also pioneered the development of the high average power fiber lasers at 976 nm and naturally proposes the patented present concept of high brightness pumping of Yb materials . The mature Yb source will produce sub-200-fs pulses and reach the average power of 100 W, with a repetition rate ranging from 5 (20 mJ) to 100 KHz (1 mJ). This source can be used both as a direct high- intensity source for HHG attosecond pulse train generation as well as a pump source for a parametric amplifier generating few cycle pulses at 2 µm and further production of isolated attosecond pulses. Despite the high volume of technological innovation envisaged in this project, its emphasis lies on demonstrating the enabling nature of these laser source in table- top high-field applications that are in dire demand for higher statistics. The 10-100 KHz multi mJ level system should open unprecedented opportunities for coincidence momentum imaging and pump-probe experiments using XUV pulses and attosecond pulse trains.

Focused beams of charged particles are essential tools for developing, modifying, analyzing, understanding and validating new concepts in nanosciences and nanotechnologies. Their uses cover a wide range of applications, controlled deposition and etching at the nanoscale, localized implantation and doping, controlled structural modifications, secondary emission imaging (electrons, ions, atoms, aggregates, molecules, photons). The vast majority of actors involved in nanotechnologies, both research laboratories and industries, are users of this technology. The needs in terms of performance and constraints can be summarized mainly by (i) the smallest possible beam sizes (< 10 nm), (ii) target intensities ranging from a single particle to a few microamperes, (iii) types and natures of particles, from the single electron to aggregates of several thousand atoms, (iv) energy ranges from eV to several hundred keV. Among these available tools, Focused Ion Beam (FIB) beams are widely used in the field of microelectronics for quality control or failure analysis during prototyping or mass production of components such as microprocessors. Thus, the market for dual beam FIB machines (equipped with a scanning electron microscope) for semiconductor companies represents a marketing of about 250 machines/year worldwide. This fleet is 95% equipped with gallium source FIB over the energy range of 3 to 30 keV. As the fineness of the semiconductor etchings is constantly evolving (< 7 nm), gallium FIBs now have limitations in use (pollution and amorphization problems). It has therefore become necessary to have non-contaminating FIBs that do not change the structure of the samples significantly. Therefore, current efforts are focused on the use of projectile ions of higher mass from rare gases (e. g. xenon) and energy below keV. The CiCLOp Joint Laboratory (CIMAP Common Laboratory with Orsay Physics), bringing together the Centre de Recherche sur les Ions, les Matériaux et la Photonique (CIMAP - CEA, CNRS, ENSICAEN et Université de Caen Normandie, UMR 6252) in Caen (14), the project leader and the ETI Orsay Physics-Tescan Orsay Holding in Fuveau (13), proposes to meet these expectations. It will rely on the research and development of original and innovative technological solutions, resulting from work and results recently acquired by each of the partners, to develop a new source of low energy ions. This technological approach will have to be based on scientific breakthroughs, which is why a scientific programme combining simulations and experiments will be deployed. The following studies are necessary: changes in the structural and physical properties of materials subjected to very intense beams, collective effects on abrasion mechanisms, stability of implanted charges and consequences on electrostatic optics generated by these charges. For each stage of the program, the results will be validated by demonstrators and valorized by technology transfers to Orsay Physics in order to lead to intermediate commercial products or devices to be integrated directly into existing systems. The herewith initial program will permit the CiCLOp joint laboratory to continue well beyond the LabCom's three-year term. In addition to the market for focused ion beam systems (FIB), well known internationally by Orsay Physics, the CiCLOP research and innovation program will address new markets such as those related to quantumtronics and future electronics. Orsay Physics will thus be able to expand its market to many application areas in France and abroad.