RESISTIVITY AND MAGNETORESISTANCE OF MONOCRYSTALLINE TASI2 AND VSI2

Refractory metal silicides can be used as protective coatings for high temperature applications as well as interconnectors in silicon integrated circuits. A good understanding of their properties as thin films, however, requires a careful determination of their intrinsic physical and mechanical characteristics. We report resistivity and magnetoresistance measurements (4.2 less-than-or-equal-to T less-than-or-equal-to 300 K, H less-than-or-equal-to 7.6 T) of monocrystalline VSi2 (RRR almost-equal-to 20) and TaSi2 (RRR greater-than-or-equal-to 400) (RRR is the residual resistance ratio rho(293 K)/rho(4.2 K)). Single crystals have been obtained by Czochralski pulling from a levitated melt. Both materials crystallize in the hexagonal C40 structure (space group P6222). The two metallic compounds have about the same anisotropic behaviour in resistivity. The measurements show a linear behaviour of resistivity at high temperatures (150 less-than-or-equal-to T less-than-or-equal-to 300 K) for the directions [0001] for both materials, whereas a negative deviation from the linearity is found at high temperatures (T greater-than-or-equal-to 200 K) with the current parallel to the [101BAR0] axis. For TaSi2 a strong magnetoresistance effect has been observed, which is about 600 times stronger than the effect for VS12.