Semiconductor, topological semimetal, indirect semimetal, and topological Dirac semimetal phases of Ge1−xSnx alloys

H.-S. Lan, S. T. Chang, C. W. Liu
2017 Physical review B  
Electronic structures of Ge$_{1-x}$Sn$_{x}$ alloys (0 $\leq$ $x$ $\leq$ 1) are theoretically studied by nonlocal empirical pseudopotential method. For relaxed Ge$_{1-x}$Sn$_{x}$, a topological semimetal is found for $\textit x$ $>$ 41$\%$ with gapless and band inversion at ${\Gamma}$ point, while there is an indirect-direct bandgap transition at $x$ = 8.5$\%$. For strained Ge$_{1-x}$Sn$_{x}$ on a Ge substrate, semimetals with a negative indirect bandgap appear for $x$ $>$ 43$\%$, and the
more » ... d Ge$_{1-x}$Sn$_{x}$ on Ge is always an indirect bandgap semiconductor for $x$ $<$ 43$\%$. With appropriate biaxial compressive strains, a topological Dirac semimetal is found with band inversion at ${\Gamma}$ and one pair of Dirac cones along the [001] direction.
doi:10.1103/physrevb.95.201201 fatcat:cpv422veinhfxkqpa6jc3uafhy