Transferability of optical bowing parameters between binary and ternary group-IV alloys

We present a detailed analysis of the compositional dependence of the average E¯1 of the E1 and E1+Δ1 transition energies in Ge1−x−ySixSny alloys. We show that this dependence can be explained in terms of three bowing parameters—bSiGe, bGeSn, and bSiSn—which scale with the product ΔχΔR of the Phillips electronegativity and size mismatches between Si, Ge, and Sn.