TY - JOUR

T1 - Density-Functional Study of the Si/SiO2 Interfaces in Short-Period Superlattices: Structures and Energies

AU - Смирнов, Михаил Борисович

AU - Рогинский, Евгений Михайлович

AU - Савин, Александр Владимирович

AU - Маженов, Нурлан

AU - Панькин, Дмитрий Васильевич

PY - 2023/7/10

Y1 - 2023/7/10

N2 - 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.

AB - 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.

KW - DFT modelling

KW - cristobalite

KW - elastic strains

KW - interface

KW - interface formation energy

KW - silicon

KW - superlattice

UR - https://doi.org/10.3390/coatings13071231

UR - https://www.mendeley.com/catalogue/8608af39-02a5-3cc8-8120-e937072f2dd6/

U2 - 10.3390/coatings13071231

DO - 10.3390/coatings13071231

M3 - Article

VL - 13

JO - Coatings

JF - Coatings

SN - 2079-6412

IS - 7

M1 - 1231

ER -