Due to its high hardness of about 35 GPa 1 , rhombohedral boron carbide , commonly denoted B4C or B13C2, here referred to as r-BxC (4 ≤ x≤ 10.5), is mainly used as a super hard material in applications such as abrasive or plate armour. Additionally, owing to the self-healing capabilities of the boron icosahedra under energetic bombardment and due to the high neutron cross-section of the isotope 10 B, it is a promising material for boron-based neutron detectors. Interestingly, and less explored, is that r-BxC is a semiconductor with electronic properties which can be tuned with the B:C stoichiometry. Its bandgap, for instance, ranges from 0.48 to 2.1 eV with increasing boron content. Semiconducting r-BxC could be used in combination with the wide bandgap materials boron subphosphide (B12P2) and boron subarsenide (B12As2) , with which it shares structural similarities, and would enable the fabrication of novel radiation resistant heterostructures. In addition, r-BxC is interesting for thermoelectric devices due to its high temperature thermoelectric properties, with a high thermal conductivity (4-10 W/m/K) and high Seebeck coefficient (150 to 300 μV/K between 500-1000 °C). Furthermore, another peculiarity of boron carbide is its ability to form crystals with fivefold symmetry due to crystal twinning. Controlled formation of these twinned crystals could be used to approximate and study boron-carbide-based quasicrystals. However, to fully explore r-BxC as a semiconductor, thin films with high crystalline quality, preferably epitaxially grown are needed, but the growth of epitaxial r-BxC crystals has proved to be challenging using vapor phase deposition techniques.