Effective strain relaxation of GeSn single crystal with Sn content of 16.5% on Ge grown by high-temperature sputtering

[Display omitted] •Sputtering epitaxy of GeSn with Sn content of 16.5% at 259 °C is achieved.•Large strain relaxation of high-Sn content GeSn is achieved with small thickness.•The strain relaxation mechanisms in constant-Sn content and step-increased-Sn content GeSn are investigated. In this work, e...

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Bibliographic Details
Published in:Applied surface science 2023-06, Vol.623, p.157086, Article 157086
Main Authors: Lin, Guangyang, Qian, Kun, Ding, Haokun, Qian, Jinhui, Xu, Jianfang, Wang, Jianyuan, Ke, Shaoying, Huang, Wei, Chen, Songyan, Li, Cheng
Format: Article
Language:English
Subjects:
Germanium tin
High temperature
high-Sn content
Sputtering
Strain relaxation
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Summary:[Display omitted] •Sputtering epitaxy of GeSn with Sn content of 16.5% at 259 °C is achieved.•Large strain relaxation of high-Sn content GeSn is achieved with small thickness.•The strain relaxation mechanisms in constant-Sn content and step-increased-Sn content GeSn are investigated. In this work, epitaxy of GeSn with high-Sn content of 16.5% on Ge substrate by sputtering at a relative high temperature of 259 °C is reported. The strain relaxation in constant-Sn content (CSC) and step-increased-Sn content (SSC) GeSn is systematically investigated. For CSC GeSn, strain mainly relaxes through generation of 60° dislocations and few 90° dislocations at Ge/GeSn interface. A defect-rich region is formed above the Ge/GeSn interface due to interaction of 60° and/or 90° dislocations, which results in associated stacking faults (SFs). For SSC GeSn, the strain relaxes preferentially through GeSn/GeSn interfaces by generation of 60° dislocations rather than through Ge/GeSn interface. The gradual strain relaxation at GeSn/GeSn interfaces eliminates bunching of dislocations and helps improve the material quality. Benefiting from the high-temperature deposition process, large strain relaxation of 85% and 65% is obtained in 120 nm CSC GeSn and 230 nm SSC GeSn, respectively. The results suggest that high-temperature sputtering epitaxy is a promising approach to prepare strain-relaxed GeSn buffer layers and promote understanding of strain relaxation mechanisms in physical vapor deposited GeSn alloys.
ISSN:0169-4332
1873-5584
DOI:10.1016/j.apsusc.2023.157086