Rhenium silicide thin films: structural analysis of the ReSi2-δ-phase

The structure of the semiconducting ReSi_2-δ phase formed in binary rhenium silicide thin films has been studied using X-ray powder diffraction. The films were deposited by magnetron cosputtering onto unheated, oxidized Si-wafers. Subsequent annealing results in crystallization of the amorphous films. By means of Rietveld analysis the unit cell dimensions and the atomic occupation factors of the crystalline phases have been determined. After annealing the film at T=973 K a ReSi_2-δ-phase phase was formed the chemical composition of which has been determined to be ReSi_1.55. Temperature enhancement gave rise to increase the occupation factors of Si resulting in an chemical composition of ReSi_1.78 at T=1073 K. This phase crystallizes with primitive space group P1 and a=0.3138 nm, b=0.3118 nm, c=0.7688 nm and α=89.83