Compositional and Strain Dependence of Effective Masses in Strained GeSn Alloys: Efficient Calculation

Abstract

Carrier effective masses under strain are vital for GeSn band engineering. Using well-established full-zone 30-band k · p and continuum elasticity theories, we calculate band-structure, density-of-states (DOS) and conductivity effective masses of Ge 1-x Sn x (0 ≤ x ≤ 0.2) under six strain modes from -1.5% compressive to 1.5% tensile. For conduction bands, L-valley transverse mass governs the modulation, while longitudinal mass is largely insensitive to Sn composition and strain; the Γ valley exhibits near-isotropic band curvature, and its effective mass generally decreases with increasing Sn composition and tensile strain. For valence bands, light hole (LH) and heavy hole (HH) masses present orientation-dependent anisotropy, and DOS/hole conductivity masses peak near zero strain. Distinct strain responses are observed for different crystallographic orientations. Benchmarks comparisons support the reliability of our calculation framework. This work reveals the orientation- and valley-dependent strain-composition coupling of carrier effective masses in strained Ge 1-x Sn x alloys, and yields a unified set of effective-mass parameters for high-performance GeSn optoelectronic device design.