In-situ study and modeling of the reaction kinetics during molecular beam epitaxy of GeO2 and its etching by Ge
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arXiv
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| Format: | Preprint |
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2023
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| author | Chen, Wenshan Egbo, Kingsley Tornatzky, Hans Ramsteiner, Manfred Wagner, Markus R. Bierwagen, Oliver |
| author_facet | Chen, Wenshan Egbo, Kingsley Tornatzky, Hans Ramsteiner, Manfred Wagner, Markus R. Bierwagen, Oliver |
| contents | Rutile GeO2 has been predicted to be an ultra-wide bandgap semiconductor suitable for future power electronics devices while quartz-like GeO2 shows piezoelectric properties. To explore these crystalline phases for application and fundamental materials investigations, molecular beam epitaxy (MBE) is a well-suited thin film growth technique. In this study, we investigate the reaction kinetics of GeO2 during plasma-assisted MBE using elemental Ge and plasma-activated oxygen fluxes. The growth rate as a function of oxygen flux is measured in-situ by laser reflectometry at different growth temperatures. A flux of the suboxide GeO desorbing off the growth surface is identified and quantified in-situ by the line-of-sight quadrupole mass spectrometry. Our measurements reveal that the suboxide formation and desorption limits the growth rate under metal-rich or high temperature growth conditions, and leads to etching of the grown GeO2 layer under Ge flux in the absence of oxygen. The quantitative results fit the sub-compound mediated reaction model, indicating the intermediate formation of the suboxide at the growth front. This model is further utilized to delineate the GeO2-growth window in terms of oxygen-flux and substrate temperature. Our study can serve as a guidance for the thin film synthesis of GeO2 and defect-free mesa etching in future GeO2-device processing. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2304_11097 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | In-situ study and modeling of the reaction kinetics during molecular beam epitaxy of GeO2 and its etching by Ge Chen, Wenshan Egbo, Kingsley Tornatzky, Hans Ramsteiner, Manfred Wagner, Markus R. Bierwagen, Oliver Materials Science Rutile GeO2 has been predicted to be an ultra-wide bandgap semiconductor suitable for future power electronics devices while quartz-like GeO2 shows piezoelectric properties. To explore these crystalline phases for application and fundamental materials investigations, molecular beam epitaxy (MBE) is a well-suited thin film growth technique. In this study, we investigate the reaction kinetics of GeO2 during plasma-assisted MBE using elemental Ge and plasma-activated oxygen fluxes. The growth rate as a function of oxygen flux is measured in-situ by laser reflectometry at different growth temperatures. A flux of the suboxide GeO desorbing off the growth surface is identified and quantified in-situ by the line-of-sight quadrupole mass spectrometry. Our measurements reveal that the suboxide formation and desorption limits the growth rate under metal-rich or high temperature growth conditions, and leads to etching of the grown GeO2 layer under Ge flux in the absence of oxygen. The quantitative results fit the sub-compound mediated reaction model, indicating the intermediate formation of the suboxide at the growth front. This model is further utilized to delineate the GeO2-growth window in terms of oxygen-flux and substrate temperature. Our study can serve as a guidance for the thin film synthesis of GeO2 and defect-free mesa etching in future GeO2-device processing. |
| title | In-situ study and modeling of the reaction kinetics during molecular beam epitaxy of GeO2 and its etching by Ge |
| topic | Materials Science |
| url | https://arxiv.org/abs/2304.11097 |