Thermoelectric properties of rhenium disilicide

Thermoelectric power and electrical conductivity have been investigated of thin films and single crystals of ReSi/sub 1.75/, a small gap semiconductor with E/sub g/=0.15 eV. The single crystals have been prepared by a modified Czochralski method, the films by facing target sputtering and reactive deposition epitaxy. The substrates used include SOS (silicon on sapphire) and Si(111) wafers. With both methods epitaxial stoichiometric ReSi/sub 1.75/ films were obtained. The films undergo a formation process during annealing up to 1000 K. They exhibit a negative thermoelectric power of about -100 /spl mu/V/K within a broad temperature range characteristic for degenerate semiconductors. The single crystals with a composition ReSi/sub 1.8/ show p-type conductivity as polycrystalline films with excess of Si. The quality of the single crystals has still to be improved to get a reference system for thin films.