Unknown

Dataset Information

0

Free-running Sn precipitates: an efficient phase separation mechanism for metastable Ge1-xSnx epilayers.


ABSTRACT: The revival of interest in Ge1-xSnx alloys with x???10% is mainly owed to the recent demonstration of optical gain in this group-IV heterosystem. Yet, Ge and Sn are immiscible over about 98% of the composition range, which renders epilayers based on this material system inherently metastable. Here, we address the temperature stability of pseudomorphic Ge1-xSnx films grown by molecular beam epitaxy. Both the growth temperature dependence and the influence of post-growth annealing steps were investigated. In either case we observe that the decomposition of epilayers with Sn concentrations of around 10% sets in above ?230?°C, the eutectic temperature of the Ge/Sn system. Time-resolved in-situ annealing experiments in a scanning electron microscope reveal the crucial role of liquid Sn precipitates in this phase separation process. Driven by a gradient of the chemical potential, the Sn droplets move on the surface along preferential crystallographic directions, thereby taking up Sn and Ge from the strained Ge1-xSnx layer. While Sn-uptake increases the volume of the melt, single-crystalline Ge becomes re-deposited by a liquid-phase epitaxial process at the trailing edge of the droplet. This process makes phase separation of metastable GeSn layers particularly efficient at rather low temperatures.

PROVIDER: S-EPMC5700949 | BioStudies |

REPOSITORIES: biostudies

Similar Datasets

2018-01-01 | S-EPMC5884787 | BioStudies
1000-01-01 | S-EPMC5150248 | BioStudies
| S-EPMC5404721 | BioStudies
| S-EPMC7011757 | BioStudies
2019-01-01 | S-EPMC6586857 | BioStudies
2016-01-01 | S-EPMC4843103 | BioStudies
2019-01-01 | S-EPMC6565697 | BioStudies
2020-01-01 | S-EPMC7589613 | BioStudies
2016-01-01 | S-EPMC4838848 | BioStudies
1000-01-01 | S-EPMC2914933 | BioStudies