Towards Direct Gap Emission in GeSn and GeC: a Hybrid Functional DFT Analysis

摘要

We use density functional theory including Heyd Scuseria Ernzerhof (HSE) hybrid functionals to investigate the electronic structure of Ge1-xSnx and Ge1-yCy supercells. The calculations confirm that a direct gap semiconductor can be obtained in the supercell calculations for low tin (x-6%) and carbon (y <; 1%) compositions. Further analysis shows strong mixing between Γand L states in the GeSn alloys for x =6.25%, close to the expected crossover between an indirect and direct gap alloy, while the lowest conduction band in the GeC alloys (y ~ 1%) also has significant indirect character.