Theoretical investigation of nitrogen-vacancy defects in silicon

Abstract

Nitrogen-vacancy defects are important for the material properties of silicon and for the performance of silicon-based devices. Here, we employ spin polarized density functional theory to calculate the minimum energy structures of the vacancy-nitrogen substitutional, vacancy-dinitrogen substitutionals, and divacancy-dinitrogen substitutionals. The present simulation technique enabled us to gain insight into the defect structures and charge distribution around the doped N atom and the nearest neighboring Si atoms. Using the dipole–dipole interaction method, we predict the local vibration mode frequencies of the defects and discuss the results with the available experimental data.

Nitrogen-Related Defects in Crystalline Silicon

“…At this point, th importance of the significantly higher electronegativity of N (3.04) as compared to Si (1.90 should be stressed. It is the reason why, in the Bader charge analysis, the Ns atom gain nearly three electrons from the nearest neighbor Si atoms (refer to Figure 1b) [54]. Th band-decomposed charge density plot for Ns (refer to Figure 1d) shows the electron den sity more clearly [54].…”

“…It is the reason why, in the Bader charge analysis, the Ns atom gain nearly three electrons from the nearest neighbor Si atoms (refer to Figure 1b) [54]. Th band-decomposed charge density plot for Ns (refer to Figure 1d) shows the electron den sity more clearly [54]. In the DOS plots, the states appearing in the bandgap are primarily due to the s electrons of Ns.…”

“…Recent DFT calculations by Kuganathan et al [54] considered bonding between th Ns (refer to Figure 1a) and the Si atoms by plotting a charge density map (refer to Figur 1c). The strong N-Si bonds have, as expected, shorter N-Si bond lengths and negativ Bader charge on Ns in the NSi4 tetrahedral unit (refer to Figure 1b) [54]. At this point, th importance of the significantly higher electronegativity of N (3.04) as compared to Si (1.90 should be stressed.…”

“…Theoretically, a lot of works have been published employed DFT as well as semiempirical calculations to gain insight into the structure, binding energies, electronic and vibrational properties, and the behavior of various nitrogen-related defects in Si [47][48][49][50][51][52][53][54][55][56][57].…”

Fabrication of nitrogen-hyperdoped silicon by high-pressure gas immersion excimer laser doping

“…Nitrogen (N)-hyperdoped silicon (Si) has emerged as a promising material with desirable electronic, spintronic, and photonic properties, offering a wide range of potential applications. N defects in Si exhibit strong sub-bandgap infrared (IR) local vibrational mode (LVM) absorptions [2][3][4][5][6][7][8][9] suitable for enhancing optoelectronics, photovoltaics, and detectors 10,11 . N also enhances oxygen precipitation and interacts significantly with vacancies, altering void size and kinetics and suppressing intrinsic defect formation [12][13][14][15][16] .…”