Ge1-xSnx alloys: Consequences of band mixing effects for the evolution of the band gap Γ-character with Sn concentration
Marko, Igor P.
O'Reilly, Eoin P.
In this work we study the nature of the band gap in GeSn alloys for use in silicon-based lasers. Special attention is paid to Sn-induced band mixing effects. We demonstrate from both experiment and ab-initio theory that the (direct) Γ-character of the GeSn band gap changes continuously with alloy composition and has significant Γ-character even at low (6%) Sn concentrations. The evolution of the Γ-character is due to Sn-induced conduction band mixing effects, in contrast to the sharp indirect-to-direct band gap transition obtained in conventional alloys such as Al1−xGaxAs. Understanding the band mixing effects is critical not only from a fundamental and basic properties viewpoint but also for designing photonic devices with enhanced capabilities utilizing GeSn and related material systems.
Electronic structure , Silicon photonics , Band mixing effects
Eales, T. D., Marko, I. P., Schulz, S., O’Halloran, E., Ghetmiri, S., Du, W., Zhou, Y., Yu, S.-Q., Margetis, J., Tolle, J., O’Reilly, E. P. and Sweeney, S. J. (2019) 'Ge1−xSnx alloys: Consequences of band mixing effects for the evolution of the band gap Γ-character with Sn concentration', Scientific Reports, 9(1), 14077. (10pp.) DOI: 10.1038/s41598-019-50349-z
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