OSIRIS project, a Research and Innovation Action (RIA), aims at improving substantially the cost effectiveness and performance of gallium nitride (GaN) based millimetre wave components. The project proposes to elaborate innovative SiC material using isotopic sources. This material will offer thermal conductivity improvement of 30% which is important for devices dissipating a lot of power, in particular in SiC power electronics and in microwave device using GaN high electron mobility transistors (HEMT) grown on SiC semi-insulating substrates. OSIRIS project will allow reinforcing GaN technology penetration into the market by cost effectiveness of the SiC substrates and circuit performances improvement thanks to better heat spreading close to the dissipative area. For microwave GaN/SiC HEMT this isotopic approach could create a complete shift in the currently used substrate / GaN epi-wafer technology; it intends to grow high thermal conductivity (+30%) semi-insulating SiC on top of low cost semiconducting SiC substrates (widely used by the power electronics and LED industries). Reduced layer thickness is necessary as only the top 50 to 100µm SiC wafer is really useful as the substrate itself is currently thinned to realise microstrip waveguided microwave circuits. For power electronics, this isotopic innovation will be essentially focused on thermal improvement, i.e. better electron mobility at a given power dissipation as mobility and drift mobility decrease with temperature and also better carrier transport thanks to lower scattering rates. Schottky and p-i-n diodes will be tested using this material, which however will have to be doped while microwave devices need semi-insulating materials. The improved thermal SiC properties will be obtained by using single isotopic atoms for silicon and carbon, namely 28Si and 12C. The SiC wafer size will be targeted to 100mm (4-inches) which is today widely used on industry.

Silicon carbide presents a high breakdown field (2-4 MV/cm) and a high energy band gap (2.3–3.2 eV), largely higher than for silicon. Within this frame, the cubic polytype of SiC (3C-SiC) is the only one that can be grown on a host substrate with the huge opportunity to grow only the silicon carbide thickness required for the targeted application. The possible growth on silicon substrate has remained for long period a real advantage in terms of scalability regarding the reduced diameter of hexagonal SiC wafer commercially available. Even the relatively narrow band-gap of 3C-SiC (2.3eV), which is often regarded as detrimental in comparison with other polytypes, can in fact be an advantage. The lowering of the conduction band minimum brings about a reduced density of states at the SiO2/3C-SiC interface and MOSFET on 3C-SiC has demonstrated the highest channel mobility of above 300 cm2/(Vxs) ever achieved on SiC crystals, prompting a remarkable reduction in the power consumption of these power switching devices. The electrical activity of extended defects in 3C SiC is a major concern for electronic device functioning. To achieve viable commercial yields the mechanisms of defects must be understood and methods for their reduction developed.. In this project new approaches for the reduction of defects will be used, working on new compliance substrates that can help to reduce the stress and the defect density at the same time. This growth process will be driven by numerical simulations of the growth and simulations of the stress reduction. The structure of the final devices will be simulated using the appropriated numerical tools where new numerical model will be introduced to take into account the properties of the new material. Thanks to these simulations tools and the new material with low defect density, several devices that can work at high power and with low power consumption will be realized inside the project.