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The effects of c-Si/a-SiO2 interface atomic structure on its band alignment: an ab initio study


The crystalline-Si/amorphous-SiO2 (c-Si/a-SiO2) interface is an important system used in many applications, ranging from transistor to solar cell. The transition region of the c-Si/a-SiO2 interface plays a critical role in determining the band alignment between this two regions. However, the question of how this interface band offset would be affected by the transition region thickness and its local atomic arrangement, has yet fully investigated. Here, by controlling the parameters of the classical Monte-Carlo bond switching algorithm, we have generated the atomic structures of the interfaces with various thickness, as well as containing Si at different oxidation states. Hybrid functional method, as shown by our calculations to reproduce the GW and experimental results for bulk Si and SiO2, are used to calculate the electronic structure of the heterojunction. This allows us to study the correlation between the interface band characterization and its atomic structures. We find that although the systems with different thickness show quite different atomic structure near the transition region, the calculated band offset tends to be the same, unaffected by the detail interfacial structure. It is shown that our band offset calculation agrees well with the experimental measurements. This robustness of the interface electronic structure to its interfacial atomic details could be another reason for the success of the c-Si/a-SiO2 interface in Si based electronics applications. Nevertheless, when the reactive force field is used to generate the a-SiO2 and the c-Si/a-SiO2 interface, the band offset significantly deviates from the experimental values by about 1 eV.

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Publication details

The article was received on 28 Aug 2017, accepted on 13 Nov 2017 and first published on 13 Nov 2017

Article type: Paper
DOI: 10.1039/C7CP05879A
Citation: Phys. Chem. Chem. Phys., 2017, Accepted Manuscript
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    The effects of c-Si/a-SiO2 interface atomic structure on its band alignment: an ab initio study

    F. Zheng, H. H. Pham and L. Wang, Phys. Chem. Chem. Phys., 2017, Accepted Manuscript , DOI: 10.1039/C7CP05879A

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