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International audience; The oxide/semiconductor structure is key to controlling current in electronic devices and HfO$_2$ is a common gate material in conventional electronic devices due to its favorable dielectric properties. Graphene devices also require insulating gates. We demonstrate a unique direct growth approach to obtain the bottom gate structure (graphene/HfO$_2$/n-SiC). The present approach involves transfer of graphene grown by chemical vapor deposition (CVD) on Cu to oxidized Si wafers, a complex process prone to low yield and reduced performance. Furthermore, HfO$_2$ is preferred to SiO$_2$ because of its superior properties. The proposed concept consists of the direct deposition of graphene by solid carbon molecular beam epitaxy on Hf metal coated n-type SiC, followed by oxygen intercalation to form HfO$_2$. The oxygen intercalation will then convert the underlying Hf into HfO$_2$ due to the strong affinity of Hf with oxygen. We identify the graphene/HfO 2 formation by Raman, X-ray photoelectron spectroscopy (XPS), Low energy electron diffraction (LEED), Low energy electron microscopy (LEEM) and electrical properties including Hall mobility and leakage current measurement.

We present a study of adsorbate screening of surface charge in microscopic ferroelectric domains in a sol-gel grown PbZr

LaB 6 eutectic materials show promise as a replacement for common thermionic cathode materials. This eutectic system belongs to a class of materials referred to as directionally solidified eutectics (DSEs). LaB 6 DSEs consist of a LaB 6 matrix with a second phase, a metal di-boride, forming cylindrical rods in the matrix. Previous investigations on this material were focused on its use as a high temperature structural material. Use as a thermionic emitter remains largely unexplored.