Epitaxial growth of Vanadium-doped SiC for back-gated graphene devices – VanaSiC

The VanaSiC project targets three complementary objectives: (i) the development of vanadium-doped SiC (SiC:V) growth on on-axis SiC substrates, (ii) the growth of graphene with an hydrogenated interface on epitaxial SiC:V back gate, and (iii) the development of two graphene-based devices exploiting this technology.
Vanadium doping (i) is a key technology to compensate residual doping in SiC epitaxial layers and to grow high resistivity films that can find many applications in electronics as well as in quantum technologies. In this project, high resistivity SiC:V epitaxial layers on n-doped on-axis substrates will be used as back gate dielectrics on which graphene monolayer or bilayer with hydrogenated interface will be grown (ii). This will allow the fine control of the charge carrier density in graphene around the neutrality point, which is currently achieved by chemical doping with low stability over time. The interest of SiC:V for applications will be demonstrated by integrating epitaxial back gates into two graphene-based devices (iii): a quantum Hall effect resistance standard (QHRS) and a graphene field effect transistor (GraFET) that will be used as a terahertz wave detector.
To achieve its objectives, the VanaSiC project brings together four laboratories and one company with complementary expertise and experimental resources. NOVASiC (SME) will grow SiC, the Centre for Research on Heteroepitaxy and Applications (CRHEA, Sophia-Antipolis) and the Laboratory Charles Coulomb (L2C, Montpellier) will grow graphene using propane/hydrogen CVD and silicon sublimation respectively. NOVASiC, CRHEA and L2C will also perform detailed characterisations of the graphene and SiC films. The QHRS and THz detectors will be fabricated by the Centre for Nanoscience and Nanotechnology (C2N, Palaiseau), and characterized by the National Metrology Laboratory (LNE, Trappes for the QHRS) and by the L2C (for the THz devices).
Many results are expected from this collaborative research project involving a company (PRCE). Once their possible applications in electronics have been demonstrated, the vanadium-doped SiC layers will constitute a new product for the NOVASiC SME. The QHRSs incorporating an epitaxial grid and operating under relaxed conditions could serve as the basis for the development of new metrological tools for the LNE, a public institute offering calibration services to industry, and in the longer term, graphene THz detectors could replace commercial detectors. More generally, a strong scientific impact is expected through open access publications resulting from the project on the growth and electronic properties of SiC and graphene, on the physics of graphene devices in general, and on THz detection and metrology applications. The impact of the project will be further enhanced by the presentation of webinars to a targeted audience of laboratories and companies likely to be interested in the results of the VanaSiC project in order to develop new knowledge and new products.