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Durham University

Department of Physics

Staff profile

Publication details for Professor Stewart Clark

Clark, SJ, Al-Allak, HM, Brand, S & Abram, RA (1998). Structure and electronic properties of FeSi2. Physical Review B 58(16): 10389-10393.

Author(s) from Durham


The nature of the band gap in the semiconducting material beta-FeSi2 is
still under some dispute. Although most experimental results indicate
the band gap to be direct, nb initio work generally reports the
material to be an indirect semiconductor with the direct transition a
few tens of millielectron volts higher than the indirect gap. However,
beta-FeSi2 is commonly grown epitaxially on a diamond-structure Si
substrate, and as a consequence, the beta-FeSi2 unit cell is strained.
Here we report the results of ab initio density-functional
calculations, which we have performed on beta-FeSi2 where its lattice
parameters are constrained according to the heteroepitaxial system
beta-FeSi2(100)/Si(001). This forms two types of lattice matching: (A)
beta-FeSi2[010] parallel to Si (110)and (B) beta-FeSi2[010] parallel to
Si(001). We find that the beta-FeSi2 band gap is highly sensitive to
its lattice parameters and therefore to the orientation at which the
material is grown on silicon. We find that type A favors a more direct
band gap, while type B has an indirect gap. [S0163-1829(98)05039-5].