Preparation and characterization of MoC x thin films

Stoichiometric MoC has been calculated to have aT_cof 16 K. To check this prediction, thin films of MoC_xwere prepared by sputtering both reactively with CH₄ and using a composite Mo-C target. The preparation conditions were varied over wide ranges of composition, substrate temperature, Ar pressure, and bias voltage. The single-phase B1 structure is formed for substrate temperatures between –100 and 1100°C withT_cvalues up to 12 K. TheT_crises with increasing lattice parametera₀. While films down to about 38 at % C were made, it was not possible to prepare samples with more than about 41 at % C in the B1 phase by this nonequilibrium technique. A linear extrapolation of theT_cversusa₀ plot yields aT_cvalue of about 26 K and ana₀ value of about 0.434 nm for stoichiometric composition. The temperature-dependent specific resistivity is discussed.