Properties of MgB$_{2}$ Thin Films Grown at Different Temperatures by Hybrid Physical-Chemical Vapor Deposition*

MgB$_{2}$ films grown by Hybrid Physical-Chemical Vapor Deposition (HPCVD) at high temperature excel in $T_{c}$, cleanness, and crystallinity. MgB$_{2}$ films have been grown at temperatures from 350$^{^{\circ}}$C to 750$^{^{\circ}}$C by a HPCVD system with separate Mg and substrate heaters. The 100 nm MgB$_{2}$ film grown on a (001) SiC substrate at 350$^{^{\circ}}$C has a $T_{c0}$ of about 36K and a residual resistance ratio of about 1.4. X-ray diffraction and atomic force microscopy show that the film is polycrystalline. The low-temperature grown MgB$_{2}$ films are promising as the top electrode for sandwich-type all-MgB$_{2}$ junctions to preserve the integrity of the barrier layer.