Electronic and spectral properties of Ge1−xSnx quantum dots

In this paper, we study theoretically the electron and spectral properties of Ge1−xSnx systems, including alloys, cubic- and spherical quantum dots. The single-particle electron and hole states are calculated within the sp3d5s∗ tight-binding approach and used in further modeling of the optical properties. We systematically study the interplay of Sn-driven indirect–direct bandgap transition and the quantum confinement effect in systems of reduced dimensionality. We demonstrate the regime of sizes and compositions, where the ground state in Ge1−xSnx quantum dots is optically active. Finally, we calculate absorbance spectra in experimentally relevant colloidal quantum dots and demonstrate satisfactory agreement with experimental data.