Electrical transport properties of transition-metal disilicide films

Electrical resistivity in the temperature range of 2-1100 K and Hall-effect measurements from 10 to 300 K of CoSi2, MoSi2, TaSi 2, TiSi2, and WSi2 polycrystalline thin films were studied. Structure, composition, and impurities in these films were investigated by a combination of techniques of Rutherford backscattering spectroscopy, x-ray diffraction, transmission electron microscopy, and Auger electron spectroscopy. These silicides are metallic, yet there is a remarkable difference in their residual resistivity values and in their temperature dependence of the intrinsic resistivities. For CoSi2, MoSi 2, and TiSi2, the phonon contribution to the resistivity was found to be linear in temperature above 300 K. At high temperatures, while a negative deviation from the linearity followed by a quasisaturation was observed for TaSi2, the resistivity data of WSi2 showed a positive deviation from linearity. It is unique that the residual resistivity, ρ(2 K), of the WSi2 films is quite high, yet the temperature dependent part, i.e., ρ(293 K) - ρ(2 K), is the smallest among the five silicides investigated. This suggests that the room-temperature resistivity of WSi2 can be greatly reduced by improving the quality of the film, and we have achieved this by using rapid thermal annealing.