Density-Functional Study of the Si/SiO2 Interfaces in Short-Period Superlattices: Structures and Energies
Smirnov M. Roginskii E. Savin A. Mazhenov N. Pankin D.
July 2023Multidisciplinary Digital Publishing Institute (MDPI)
Coatings
2023#13Issue 7
The oxide-semiconductor interface is a key element of MOS transistors, which are widely used in modern electronics. In silicon electronics, SiO2 is predominantly used. The miniaturization requirement raises a problem regarding the growing of heterostructures with ultrathin oxide layers. Two structural models of interface between crystalline Si and cristobalite SiO2 are studied by using DFT-based computer modelling. The structures of several Si/SiO2 superlattices (SL), with layer thicknesses varied within 0.5–2 nm, were optimized and tested for stability. It was found that in both models the silicon lattice conserves its quasi-cubic structure, whereas the oxide lattice is markedly deformed by rotations of the SiO4 tetrahedra around axes perpendicular to the interface plane. Based on the analysis of the calculated total energy of SLs with different thicknesses of the layers, an assessment of the interface formation energy was obtained. The formation energy is estimated to be approximately 3–5 eV per surface Si atom, which is close to the energies of various defects in silicon. Elastic strains in silicon layers are estimated at 5–10%, and their value rapidly decreases as the layer thickens. The elastic strains in the oxide layer vary widely, in a range of 1–15%, depending on the interface structure.
cristobalite , DFT modelling , elastic strains , interface , interface formation energy , silicon , superlattice
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Faculty of Physics, Saint-Petersburg State University, Universitetskaya Nab. 7/9, Saint Petersburg, 199034, Russian Federation
Ioffe Institute, Politehnicheskaya St. 26, Saint Petersburg, 194021, Russian Federation
Faculty of Power Engineering, Automation and Telecommunications, Abylkas Saginov Karaganda Technical University, Nursultan Nazarbayev Ave. 56, Karaganda, 100027, Kazakhstan
Center for Optical and Laser Materials Research, Research Park, Saint-Petersburg State University, Universitetskaya Nab. 7/9, Saint Petersburg, 199034, Russian Federation
Faculty of Physics
Ioffe Institute
Faculty of Power Engineering
Center for Optical and Laser Materials Research
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