Experimental and theoretical band-structure studies of refractory metal silicides

The electronic structures of bulk refractory metal disilicides V${\mathrm{Si}}_2$, Ta${\mathrm{Si}}_2$, and Mo${\mathrm{Si}}_2$ have been examined using photoelectron spectroscopy with synchrotron radiation. Photoelectron energy distribution curves measured for $9\le \mathrm{hv}\le 140$ eV show occupied bands (full width $\simeq 12$ eV) dominated by metal $d$-derived states within 3-4 eV of $E_F$ and by $\mathrm{Si}3s$- and $3p$-derived features at higher binding energies. The $\mathrm{V}3p$, $\mathrm{Mo}4p$, $\mathrm{Ta}5p$, $\mathrm{Ta}4f$, and $\mathrm{Si}2p$ coreemission features are also shown. Self-consistent band calculations for a series of cubic silicides $M{\mathrm{Si}}_3$, $M\mathrm{Si}$, and $M_3\mathrm{Si}$ ($M$ denotes V or Mo) predict dominant metal $d$ character within 5 eV of $E_F$, $\mathrm{Si}s$ states centered at about - 10 eV, $\mathrm{Si}p$ states centered near - 5 eV, and substantial $M-\mathrm{S}\mathrm{i}$ hybridization, in agreement with experiment.