Study on the Influence of Sn Concentration on Non-Substitutional Defect Concentration and Sn Surface Segregation in GeSn Alloys
GeSn alloys are among the most promising materials for the fabrication of high-efficiency silicon-based light sources. However, due to the tendency of Sn to segregate to the surface during growth, it is challenging to achieve a high Sn concentration while maintaining high-quality GeSn alloys. Both t...
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2025-04-01
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| author | Zihang Zhou Jiayi Li Mengjiang Jia Hai Wang Wenqi Huang Jun Zheng |
| author_facet | Zihang Zhou Jiayi Li Mengjiang Jia Hai Wang Wenqi Huang Jun Zheng |
| author_sort | Zihang Zhou |
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| description | GeSn alloys are among the most promising materials for the fabrication of high-efficiency silicon-based light sources. However, due to the tendency of Sn to segregate to the surface during growth, it is challenging to achieve a high Sn concentration while maintaining high-quality GeSn alloys. Both theoretical and experimental studies have confirmed that non-substitutional Sn defects (VSnV) are the primary driving factors in Sn surface segregation. However, there is a discrepancy between existing theoretical and experimental findings regarding the variation in VSnV concentration with total Sn concentration. To clarify this issue, we first prepared GeSn materials with varying Sn concentrations using molecular beam epitaxy (MBE) and subjected them to annealing at different temperatures. Subsequently, we characterized the VSnV concentration and Sn surface segregation. The results indicate that a higher total Sn concentration and temperature lead to an increased VSnV concentration, and the proportion of VSnV relative to the total Sn concentration also increases, which is consistent with existing theoretical research. To explain these phenomena, we employed first-principles calculations based on density functional theory (DFT) to investigate the effect of varying the total Sn concentration on the formation of substitutional Sn (Sn<sub>s</sub>) and VSnV in GeSn alloys, while simultaneously studying the migration kinetics of Sn atoms. The results demonstrate that as the total Sn concentration increases, the formation of Sn<sub>s</sub> becomes more difficult, while the formation of VSnV becomes easier, and Sn atoms exhibit enhanced migration tendencies. The analysis of binding energies and charge density distribution maps reveals that this is due to the weakening of Ge-Sn bond strength with increasing Sn concentration, whereas the binding strength of VSnV exhibits the opposite trend. These findings demonstrate excellent agreement with experimental observations. This study provides both theoretical and experimental references for GeSn material growth and VSnV defect control through a combined theoretical–experimental approach, offering significant guidance for enhancing device performance. |
| format | Article |
| id | doaj-art-c12e46612fc74e4b8486b6921611e635 |
| institution | DOAJ |
| issn | 1420-3049 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj-art-c12e46612fc74e4b8486b6921611e6352025-08-20T02:58:47ZengMDPI AGMolecules1420-30492025-04-01309187510.3390/molecules30091875Study on the Influence of Sn Concentration on Non-Substitutional Defect Concentration and Sn Surface Segregation in GeSn AlloysZihang Zhou0Jiayi Li1Mengjiang Jia2Hai Wang3Wenqi Huang4Jun Zheng5School of Applied Science, Beijing Information Science and Technology University, Beijing 102206, ChinaKey Laboratory of Optoelectronic Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, ChinaSchool of Applied Science, Beijing Information Science and Technology University, Beijing 102206, ChinaSchool of Applied Science, Beijing Information Science and Technology University, Beijing 102206, ChinaSchool of Applied Science, Beijing Information Science and Technology University, Beijing 102206, ChinaKey Laboratory of Optoelectronic Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, ChinaGeSn alloys are among the most promising materials for the fabrication of high-efficiency silicon-based light sources. However, due to the tendency of Sn to segregate to the surface during growth, it is challenging to achieve a high Sn concentration while maintaining high-quality GeSn alloys. Both theoretical and experimental studies have confirmed that non-substitutional Sn defects (VSnV) are the primary driving factors in Sn surface segregation. However, there is a discrepancy between existing theoretical and experimental findings regarding the variation in VSnV concentration with total Sn concentration. To clarify this issue, we first prepared GeSn materials with varying Sn concentrations using molecular beam epitaxy (MBE) and subjected them to annealing at different temperatures. Subsequently, we characterized the VSnV concentration and Sn surface segregation. The results indicate that a higher total Sn concentration and temperature lead to an increased VSnV concentration, and the proportion of VSnV relative to the total Sn concentration also increases, which is consistent with existing theoretical research. To explain these phenomena, we employed first-principles calculations based on density functional theory (DFT) to investigate the effect of varying the total Sn concentration on the formation of substitutional Sn (Sn<sub>s</sub>) and VSnV in GeSn alloys, while simultaneously studying the migration kinetics of Sn atoms. The results demonstrate that as the total Sn concentration increases, the formation of Sn<sub>s</sub> becomes more difficult, while the formation of VSnV becomes easier, and Sn atoms exhibit enhanced migration tendencies. The analysis of binding energies and charge density distribution maps reveals that this is due to the weakening of Ge-Sn bond strength with increasing Sn concentration, whereas the binding strength of VSnV exhibits the opposite trend. These findings demonstrate excellent agreement with experimental observations. This study provides both theoretical and experimental references for GeSn material growth and VSnV defect control through a combined theoretical–experimental approach, offering significant guidance for enhancing device performance.https://www.mdpi.com/1420-3049/30/9/1875GeSn alloyssubstitutional Snnon-substitutional Sn defectssurface segregationformation energy |
| spellingShingle | Zihang Zhou Jiayi Li Mengjiang Jia Hai Wang Wenqi Huang Jun Zheng Study on the Influence of Sn Concentration on Non-Substitutional Defect Concentration and Sn Surface Segregation in GeSn Alloys Molecules GeSn alloys substitutional Sn non-substitutional Sn defects surface segregation formation energy |
| title | Study on the Influence of Sn Concentration on Non-Substitutional Defect Concentration and Sn Surface Segregation in GeSn Alloys |
| title_full | Study on the Influence of Sn Concentration on Non-Substitutional Defect Concentration and Sn Surface Segregation in GeSn Alloys |
| title_fullStr | Study on the Influence of Sn Concentration on Non-Substitutional Defect Concentration and Sn Surface Segregation in GeSn Alloys |
| title_full_unstemmed | Study on the Influence of Sn Concentration on Non-Substitutional Defect Concentration and Sn Surface Segregation in GeSn Alloys |
| title_short | Study on the Influence of Sn Concentration on Non-Substitutional Defect Concentration and Sn Surface Segregation in GeSn Alloys |
| title_sort | study on the influence of sn concentration on non substitutional defect concentration and sn surface segregation in gesn alloys |
| topic | GeSn alloys substitutional Sn non-substitutional Sn defects surface segregation formation energy |
| url | https://www.mdpi.com/1420-3049/30/9/1875 |
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