An Extended Hückel Theory Parameter Set for Efficient Electronic Structure Calculations of SiGe Alloys

A new parameterization for Si and Ge in the framework of the extended Hückel theory (EHT) is presented and its application in calculating the band structure of strained and unstrained SiGe alloys with varying Ge content is shown. The variation of the bandgap and electron/hole effective masses caused by the random distribution of Si and Ge atoms in the alloy is investigated. The parameter set is further verified by combining it with an existing parameterization for C, highlighting the key advantage of EHT over standard tight binding methods: the atom‐centered EHT approach allows an easy combination of parameter sets. By unfolding the alloy supercell band structure back into the primitive cell Brillouin zone, the effect of alloy composition on the electronic structure is visualized and the effect of neighboring C atoms on the bandgap is investigated.