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.