PROPERTIES OF SEMICONDUCTING RHENIUM SILICIDE THIN-FILMS GROWN EPITAXIALLY ON SILICON(111)

The optical and transport properties of rhenium silicide thin films ep itaxially grown on Si(111) have been studied. On the one hand, the ana lysis of the optical spectrum above the band gap energy confirms the s emiconducting character of the samples. Moreover, the absorption coeff icient prefactor measured for films of various thicknesses in the rang e of 50-475 Angstrom depend on the thickness itself, possibly reflecti ng a two-dimensional quantization of states related to the existence o f a quantum well due to the band offsets at the heterojunction. On the other hand, electrical measurements on high resistivity silicon subst rates are explained by the existence of an impurity band, The concentr ation of electrically active impurities decreases by one order of magn itude when the sample is annealed at 850 degrees C under a hydrogen pa rtial pressure.