MgB/sub 2/ thin films grown at different temperatures by hybrid physical-chemical vapor deposition

We have grown MgB/sub 2/ films at different substrate temperatures by hybrid physical-chemical vapor deposition. X-ray diffraction analysis shows epitaxial growth at all temperatures, as measured at the substrate surface, between 550-700/spl deg/C. An optimal deposition temperature was found around 650/spl deg/C, at which the rocking curve is the narrowest, the residual resistivity is the lowest, and T/sub c/ is the highest. For the films deposited at lower temperatures, the rocking curve broadens, indicating a decreasing quality of crystallinity. The residual resistivity increases but the superconducting transition temperature remains nearly constant around 40 K when the deposition temperature is decreased to 550/spl deg/C. The deposition of epitaxial films with excellent superconducting properties at low substrate temperatures is important for device and circuit processing utilizing MgB/sub 2/.