Electronic structure of silicon nitride

Journal of Physics: Condensed Matter, 2001

Results of first-principles band-structure calculations for the ternary alkalineearth silicon nitrides M 2 Si 5 N 8 (M = Ca and Sr) are presented. In the structures of M 2 Si 5 N 8 (M = Ca, Sr and Ba), the N atoms show connections to two (N [2] ) and three (N [3] ) neighbouring silicon tetrahedral centres. Calculations show that the local electronic structure is strongly dependent on the local chemical bonding. The valence band is dominated by N 2p hybridized with the s, p states of the alkaline-earth-metal and silicon atoms. The upper part of the valence band is dominated by the 2p states of N [2] atoms, while the N [3] 2p states lie about 2 eV below the Fermi level. The bottom of the conduction band consists of the N 3s characters hybridized with s orbitals of the alkaline-earth metals, while the s character of Si atoms is higher in energy. Sr 2 Si 5 N 8 is a semiconductor with a direct energy gap at , while Ca 2 Si 5 N 8 is an indirect semiconductor. Optical diffuse reflectance spectra show an energy gap of 4.9 eV for Ca 2 Si 5 N 8 , 4.5 eV for Sr 2 Si 5 N 8 , as well as 4.1 eV for Ba 2 Si 5 N 8 , in fair agreement with the calculated values.

Applied Physics Letters, 2011

We apply soft x-ray emission spectroscopy (XES) to measure the electronic structure of crystalline silicon supersaturated with sulfur (up to 0.7 at. %), a candidate intermediate-band solar cell material. Si L 2,3 emission features are observed above the conventional Si valence band maximum, with intensity scaling linearly with S concentration. The lineshape of the S-induced features change across the insulator-to-metal transition, indicating a significant modification of the local electronic structure concurrent with the change in macroscopic electronic behavior. The relationship between the Si L 2,3 XES spectral features and the anomalously high sub-band gap infrared absorption is discussed.

MRS Proceedings, 1990

ABSTRACTUsing a first principles pseudopotential total energy approach with a localized basis for the electronic wave functions, we have investigated the structural and bonding properties of β-Si3N4 and β-C3N4, which is a proposed structure for carbon nitride. The latter system is used as a prototype for studying the properties of possible covalent C-N solids. For β-Si3N4, calculated structural properties such as lattice constant and bulk modulus are in excellent agreement with experimental values. This gives support for the predicted properties of β-C3N4.β/C3N4 is found to be a good candidate for a new low-compressibility solid, with compressibility comparable to diamond. Despite similarities between β-Si3N4 and β-C3N4 in terms of crystal structure and valency of constituent elements, differences are found in their electronic bonding properties. A comparison of the bonding in β-Si3N4 and β-C3N4 with other first and second row semiconductors is useful for understanding trends in the...

Applied Surface Science, 1991

The interface state density along the semiconductor energy gap and the fixed charge were evaluated in SiNx/InGaAs and SiNx/Si interfaces. The insulator layer was deposited by plasma-enhanced chemical vapour deposition (PECVD) using several ammonia/silane gas ratios. In both the samples the measurements revealed two main peaks of interface states whose height is a function of the insulator layer stoichiometry. Further analysis by infrared and Auger electron spectroscopy and electron spin resonance measurements enabled the peaks to be identified as the two silicon-related defects in silicon nitride cited in the literature. The nitrogen dangling bonds were found to affect the fixed charge of the structure. The role of hydrogen in passivating silicon and nitrogen dangling bonds will also be discussed.

Thin Solid Films, 2010

This work presents first-principles calculations of electronic structure and optical properties of doped α-Si 3 N 4. It is found that B and P impurities form shallow acceptor and deep donor bands, respectively, in the band gap of α-Si 3 N 4. Analysis of the charge neutrality level indicates that bipolar doping of α-SiN x is possible and that both n-and p-type electrical conductivity can be expected. This result can be helpful to extend the list of device applications of SiN x. Furthermore, it is shown that upon heavy doping with these impurities, the optical properties of the material are modified by doping. Both the refractive index and extinction coefficients are increased over the photon energy range 0-4 eV as a result of the doping.

Materials Science-Poland, 2016

Hydrogen, amorphous silicon nitride (SiNx:H abbreviated SiNx) films were grown on multicrystalline silicon (mc-Si) substrate by plasma enhanced chemical vapour deposition (PECVD) in parallel configuration using NH3/SiH4 gas mixtures. The mc-Si wafers were taken from the same column of Si cast ingot. After the deposition process, the layers were oxidized (thermal oxidation) in dry oxygen ambient environment at 950 °C to get oxide/nitride (ON) structure. Secondary ion mass spectroscopy (SIMS), Rutherford backscattering spectroscopy (RBS), Auger electron spectroscopy (AES) and energy dispersive X-ray analysis (EDX) were employed for analyzing quantitatively the chemical composition and stoichiometry in the oxide-nitride stacked films. The effect of annealing temperature on the chemical composition of ON structure has been investigated. Some species, O, N, Si were redistributed in this structure during the thermal oxidation of SiNx. Indeed, oxygen diffused to the nitride layer into Si2O...

Diamond and Related Materials, 2004

First-principles calculations have been carried to study the structural and electronic properties of the series of a-silicon carbon nitride crystals which have been successfully synthesized and demonstrate interesting mechanical, electronic, optical properties. The bulk modulus values of the SiCN structures have been observed to progressively increase up as more C atoms substituted for Si atoms in the crystal due to strong covalent C-N bonds compared to Si-N bonds. The band structure calculations indicate that the electronic properties of the a-SiCN crystals are closer to a-Si N than to a-C N . In addition, to improve the 3 4 3 4 underestimation of local density approximation, we implement the generalized density functional scheme to correct the band gap values for SiCN crystals. The size of the band gap for a-Si CN after gap opening shows a value of 3.82 eV which demonstrates 2 4