The project fits into the economic development strategy for alternative and sustainable sources of energy. The energy that we want to harvest in this project are ‘truly free’ mechanical sources like fluid flows (like wind or river), parasitic vibration (in engines or rotating machines, for example) or human movements (voluntary motion like walking or hand movements). The main applications are low consumption nomad electronics and remote wireless sensors. The heart of the project is to develop a prototype that integrates, on the same flexible chip, a microgenerator that converts this ambient mechanical energy into electrical energy that can recharge a lithium battery, through a specific electrical converter. Since the efficiency of such a mechanical harvesting device strongly depends on the matching between: a piezoelectric microgenerator (called PG), the power management block (called PMB), the electrical load block (a Li battery called LiB), we propose in this project to have an integrative approach: studying and designing the whole energy conversion chain. The geometry of the final prototype is already fixed: 5 x 2,5 cm2 on flexible substrate (ISO 7816 smart card international standard), corresponding to the dimensions of the flexible LiB currently being developed by ST. The objective is to reach 150 µW at the output of the PMB, which is the minimum power necessary to charge the LiB. Given the efficiency (around 55%) of existing PMBs at low current, the PG is asked to provide a minimum 280 µW to the PMB. This performance is consistent with small indoor photovoltaic cell (27cm2) that provides 200 µW 6 hours a day in office conditions (cf. PowerFilm). These harvesters already power existing applications : e.g. 3 activated sensors and a RF signal every 10 minutes. Hence, a PG working 8 hours a day and providing an average 280 µW can power the same loads as already addressed by the PowerFilm cell. Now if vibrating energy is only available 40 minutes a day, there is still niche applications where the 280 uW harvester can fit, like autonomous switch for lighting (cf. ECS300 from EnOcean : a simple message is sent 30 meters away every time a switch is pressed). So the 280 µW dimensioning covers realistic cases of load, with an energy availability ranging from 40 minutes to 8 hours. GREMAN has a well-known expertise in all the aspects of piezoelectricity, and more specifically on piezoelectric nanowires for more than 5 years. It has started by modelling aspects and it is reaching now the level of ZnO-based PGs. The whole device is designed and fabricated in GREMAN: growth of the ZnO nanowires, device fabrication and characterization. GREMAN’s technology is now mature enough on silicon substrates to be optimised for specific applications, specific loads and specific flexible substrates. STMicroelectronics Tours aims to be a world-class center of expertise for designing and manufacturing electronic components for providing storage solutions and intelligent energy management. ST Tours is now considering different energy harvesting solutions including photovoltaic, vibratory and thermoelectric means. In this context, ST Tours sells LiCoO2/LiPON/Li microbatteries. They are already relatively flexible, suitable for the ISO 7816 standard. Moreover, ST has already developed a PMB able to charge the Li microbattery. This PMB is a non flexible CMOS on silicon wafer prototype device, based on robust BCD6s technology (size 3 x 3 x 1 mm3). Finally, ST posses in Tours a “packaging lab” which has a long term expertise in reporting such devices on flexible modules, making the appropriate electrical interconnections. All the equipment, the knowledge and the technological bricks to reach our goal are available on the same site shared by ST and GREMAN in Tours. The consortium GREMAN - ST Tours has a solid experience of cooperation through several projects and 22 joint CIFRE PhD projects, which have led to more than 50 publications and 10 patents.

Nowadays, due to the rapid development of wireless communication systems, in particular, public telecommunication, such as, television, internet, mobile phones and global positioning systems (GPS), transceiver architectures demand constant miniaturization of millimeter wave and microwave devices , better integration , lower power consumption and low cost. For this reason, the next generation wireless communication systems turn toward multi-function modules by incorporating reconfigurable and tunable structures. This project aims to explore new ways in order to achieve a telecommunication system with size miniaturization and complex functionality. In this view, this project proposes to use nanotechnology to realize innovative microwave components using the ferroelectric titanate of barium and Strontium Ba1-xSrxTiO3 (BST). BST is a ferroelectric tunable material at room temperature and can be used to achieve multiple applications in circuit design and tunable devices. To achieve the goals of this project, simultaneous efforts in materials development, process technologies and device designs are required to obtain a high-quality Radio Frequency (RF) system with tunable, compact, highly integrated, reliable, temperature stable components, in addition to good power handling capabilities. To develop such innovative devices, it is necessary that engineers and researchers in advanced materials and micro-electronics work in conjunction with telecommunication industry. This project aims to achieve a new level of tunable BST technology for microwave components, such as tunable filters, antennas, and capacitors. Concerning the materials, our effort will concern the optimization of the electrodes, the structure and microstructure of the ferroelectric and the interfaces quality in the components. At a fundamental level, it is important to study the best technological conditions with respect to type of substrate, thickness of BST, and BST optimization to design the proposed components, namely filters, antennas and capacitors. In the design level, different structure topologies and design schemes should be studied to achieve maximum tunability with minimum size and power consumption. The work plan is based on technology optimization that is suitable for different microwave components including the fabrication of BST, the selection of technology and optimal design whose results will be used in the implementation of more complex structures and devices. In this project we target the presentation of new functionality and performance of BST based RF and microwave components with respect to miniaturization, multiple functionality and power handling capabilities.

The MOCA project is dedicated to the study of thin films single crystals from the perovskite family obtained on Silicon substrate by epitaxial routes. The materials developed will be Pb(Zr,Ti)O3 (PZT) with Zr/Ti=52/48 and (Ba,Sr)TiO3 (BST) with Ba/Sr=70/30. Three different deposition techniques will be performed: Molecular Beam Epitaxy (MBE), sol gel and Pulsed Laser Deposition (PLD). The targeted proofs of concept are three fold: acoustic resonators, high-K capacitors and piezoelectric actuators. The final aim of MOCA is to provide a clear status on the superiority of the epitaxial single crystal thin films compared to their polycrystalline counterpart. Four partners will be involved in MOCA. CEA LETI Minatec will be the leader of the project and will process the sol gel layers (PZT and BST) deposited on SrTiO3 (STO) buffered layers, which is mandatory to obtain single crystals on Si. LETI will also realise several proof of concepts devices: resonators with FEMTO, capacitors and piezoelectric or electrostrictive actuators. He will characterize these devices. INL will bring his expertise on MBE to the consortium. He will prepare the template Si wafers with the STO layer and will work specifically on this template layer. He will also prepare BST active layers in order to compare their properties to the one obtained with the other techniques. A demonstrator will be done by the partners (actuators or/and resonators). INL will provide the template layers to the partners. SPMS will work on the PLD route as it is also a recognized way to obtain single crystals as thin films. He will also help the consortium to characterize the structural behaviour of the layers deposited. FEMTO will realize resonators and characterize them. The consortium is very complementary on this dedicated topic of perovskite single crystal on Si. Finally, ST Tours, industrial with a long experience of integrating PZT capacitors with Si, will elaborate specifications and will test the capacitors based on single crystals perovskite in the framework of the MOCA project. The partners have already several common projects and developed the know-how to work together for a long time.

The 2DTherm project tackles the ability to use Raman spectroscopy of two-dimensional materials to act as absolute nanoscale temperature probes for the development of power electronics on SiC and GaN. Indeed, current densities are such that local temperature can reach up to 350°C under certain operational conditions in these devices. Probing the local temperature is thus a crucial element as it impacts their lifetimes, degradation mechanisms and device performances. However, conventional approach by thermal simulation and infrared mapping is not sufficient as it only measures the temperature gradients. Here we propose that by using 2D materials on the device surface, very precise absolute temperatures measurements should be made possible thanks to the Raman technique (using the ratio of Stokes/Antistokes peaks or the Stokes peaks position). As a proof of concept our technique will be applied to the latest generation of power devices from STMicroelectronics. To do this, the consortium will explore the most interesting 2D materials in terms of deposition (PLD, CVD..), transfer on transistor (local buffer, pick and place, spray), Raman signature and electrical and thermal properties, and this on real bare chips and transistors in de-encapsulated plastic case. The local absolute temperature measurements will eventually allow to correct the thermal simulations, to refine the electrothermal models of the transistors to ensure the performance of the systems in a concern of reliability with cost and energy saving (dimensioning of the cooling systems) for greener electronics.