Electronic Transport Properties of Tantalum Disilicide Thin Films

摘要

Polycrystalline TaSi2 thin films were prepared by furnace reaction of ion beam sputtered tantalum layers with silicon surfaces. X-ray diffraction measurements indicate that the films are single phase hexagonal disilicide. Impurity levels are at or below the detection limits of Auger spectroscopy. The samples exhibit a room temperature intrinsic resistivity of approx. 40 microohms cm and a residual resistivity component as low as 4 microohms cm. The Hall coefficient is negative, giving an apparent electron concentration of 6.5x to the 22nd power/cu cm at room temperature. A representative carrier mobility of 58 sq cm/V s at room temperature (obtained from geometrical magnetoresistance measurements) was much larger than the Hall mobility (1.9 sq cm/V s), suggesting multicarrier effects. The galvanomagnetic properties can be described by the equations for two degenerate, isotropic bands and be given a physical interpretation similar to that of Mott's s-d scattering model. However, it is emphasized that the two-band model is likely only a crude approximation for transition metals and their compounds. A two-layer model shows that in certain instances the apparent transport properties of the films are due to the silicon substrate.