Transport properties of LixTiS2 (O<x;<1): A metal with a tunable Fermi level

TiS2 is an extrinsic semiconductor with a layered structure, between the layers of which a variety of electron donor species, such as lithium, may be intercalated. In the rigid-band model of intercalation, the lithium atoms simply donate charge to the rigid energy bands of the host material and intercalation thus provides a convenient way to tune the Fermi level. In this way the properties of LixTiS2 may be varied smoothly from those of an extrinsic semiconductor (x=O) to those of a metal (x=1). Our transport measurements confirm the usefulness of the rigid-band model over the range 0<;or= x <or=1. The dependence of the resistivity of LixTiS2 on temperature and carrier concentration is discussed in terms of a combination of intra- and inter-valley electron-LA-phonon scattering below room temperature and resonant scattering between electrons and inter-layer ionised Ti impurities at very low temperatures.