Superconducting $MgB2$ thin films on silicon carbide substrates by hybrid physical–chemical vapor deposition

We have used two polytypes of silicon carbide single crystals, 4H-SiC and 6H-SiC, as the substrates for $MgB2$ thin films grown by hybrid physical-chemical vapor deposition (HPCVD). The c-cut surface of both polytypes has a hexagonal lattice that matches closely with that of $MgB2.$ Thermodynamic calculations indicate that SiC is chemically stable under the in situ deposition conditions for $MgB2$ using HPCVD. The $MgB2$ films on both polytypes show high-quality epitaxy with a Rutherford backscattering channeling yield of 12%. They have $Tc$ above 40 K, low resistivities, high residual resistivity ratios, and high critical current densities. The results demonstrate that SiC is an ideal substrate for $MgB2$ thin films.