Defect levels of dangling bonds in silicon and germanium through hybrid functionals

2008 ◽  
Vol 78 (7) ◽  
Author(s):  
Peter Broqvist ◽  
Audrius Alkauskas ◽  
Alfredo Pasquarello
Keyword(s):  
Dangling Bonds ◽  
Hybrid Functionals ◽  
Defect Levels ◽  
Silicon And Germanium

scholarly journals Defects in SiC for Quantum Computing

MRS Advances ◽  
2019 ◽  
Vol 4 (40) ◽  
pp. 2217-2222
Author(s):  
Renu Choudhary ◽  
Rana Biswas ◽  
Bicai Pan ◽  
Durga Paudyal
Keyword(s):  
Band Gap ◽  
Valence Band ◽  
Density Functional ◽  
Single Photon ◽  
Band Edge ◽  
Valence Band Edge ◽  
Dangling Bonds ◽  
Defect Levels ◽  
Formation Energies ◽  
Qubit Operation

AbstractMany novel materials are being actively considered for quantum information science and for realizing high-performance qubit operation at room temperature. It is known that deep defects in wide-band gap semiconductors can have spin states and long coherence times suitable for qubit operation. We theoretically investigate from ab-initio density functional theory (DFT) that the defect states in the hexagonal silicon carbide (4H-SiC) are potential qubit materials. The DFT supercell calculations were performed with the local-orbital and pseudopotential methods including hybrid exchange-correlation functionals. Di-vacancies in SiC supercells yielded defect levels in the gap consisting of closely spaced doublet just above the valence band edge, and higher levels in the band gap. The divacancy with a spin state of 1 is charge neutral. The divacancy is characterized by C-dangling bonds and a Si-dangling bonds. Jahn-teller distortions and formation energies as a function of the Fermi level and single photon interactions with these defect levels will be discussed. In contrast, the anti-site defects where C, Si are interchanged have high formation energies of 5.4 eV and have just a single shallow defect level close to the valence band edge, with no spin. We will compare results including the defect levels from both the electronic structure approaches.

Study of the Location of Implanted Fluorine Atoms in Silicon and Germanium through Their Nuclear Quadrupole Interactions

1996 ◽  
Vol 51 (5-6) ◽  
pp. 560-564 ◽  
Author(s):  
Stacie S. Nunes ◽  
S. Sulaiman ◽  
N. Sahoo ◽  
T. P. Das ◽  
M. Frank ◽  
...  
Keyword(s):  
Minimum Energy ◽  
Wave Functions ◽  
Dangling Bonds ◽  
Hyperfine Parameters ◽  
Frequency Signal ◽  
Crystalline Materials ◽  
Hartree Fock ◽  
Surface Sites ◽  
Nuclear Quadrupole ◽  
Silicon And Germanium

Abstract Time Differential Perturbed Angular Distribution (TDPAD) measurements of the nuclear quadrupole hyperfine parameters for 19F* implanted into amorphous, polycrystalline and crystalline silicon and germanium are reported and reviewed. Two signals are observed in the crystalline materials (≈ 35 and 23 MHz in silicon, ≈ 33 and 27 MHz in germanium) while only one is detected in the amorphous and polycrystalline samples (≈ 22 MHz in silicon, ≈ 27 in germanium). Impurity sites in these materials were modeled using a Hartree-Fock cluster procedure. The Intrabond, Antibond, and Substitutional sites in the bulk were studied in both silicon and germanium. The ATOP and Intrabond Surface sites were also studied in silicon and the results extended to germa-nium. Lattice relaxation effects were incorporated by employing a geometry optimization method to obtain minimum energy configurations for the clusters modelling each site. The electronic wave functions were obtained for each optimized cluster by applying Unresctricted Hartree-Fock theory, and these wave functions were used to calculate the nuclear quadrupole hyperfine parameters at the site of the fluorine nucleus. Comparison of the theoretical hyperfine parameters to the experimental values indicates that 19F* located in the Intrabond and Intrabond surface sites could readily explain the higher frequency signal that has been observed. 19F* in the Antibond and the surface ATOP sites yield hyperfine parameters consistent with the low frequency signal observed in the crystalline materials and the single signal observed in the amorphous (or polycrystalline) materials. Examina-tion of these two sites, in view of other available experimental evidence including the temperature dependence of the TDPAD signals, leads to the conclusion that the lower frequency signal is due to 19F* implants which have come to rest at the site of dangling bonds in the bulk. These dangling bonds are created as a result of damage generated in the individual collision cascades during the implantation process.

Dislocation Nucleation Models From Point Defect Condensations in Silicon and Germanium

1980 ◽  
Vol 2 ◽  
Author(s):  
T.Y. Tan
Keyword(s):  
Point Defect ◽  
Point Defects ◽  
Strain Energy ◽  
Dislocation Nucleation ◽  
Dominant Factor ◽  
Dangling Bonds ◽  
Configurational Energy ◽  
Nucleation Stage ◽  
Partial Dislocations ◽  
Silicon And Germanium

ABSTRACTThe process of dislocation nucleation from point defect condensations in Si(Ge) is discussed. Based on the assumption that during the dislocation nucleation stage, the dominant factor in the configurational energy is the number of dangling bonds per point defect incorporated, rather than the more commonly recognized factor of strain energy, it is possible to model the dislocation nucleation process. In order to minimize the number of dangling bonds, point defects would condense into row configurations elongated in <110>, called intermediate defects (IDC), and then the IDCs would evolute into undissociated 90° edge –, 60°, and Frank partial dislocations.

Identification of defect levels at As/oxide interfaces through hybrid functionals

2011 ◽  
Vol 88 (7) ◽  
pp. 1436-1439 ◽  
Author(s):  
Hannu-Pekka Komsa ◽  
Alfredo Pasquarello
Keyword(s):  
Oxide Interfaces ◽  
Hybrid Functionals ◽  
Defect Levels

scholarly journals Defect levels of carbon-related defects at the SiC/SiO2interface from hybrid functionals

2011 ◽  
Vol 83 (19) ◽  
Author(s):  
Fabien Devynck ◽  
Audrius Alkauskas ◽  
Peter Broqvist ◽  
Alfredo Pasquarello
Keyword(s):  
Hybrid Functionals ◽  
Defect Levels

Investigation of irradiation-induced nucleation processes in silicon and germanium

1995 ◽  
Vol 53 ◽  
pp. 224-225
Author(s):  
Harry A. Atwater ◽  
C.M. Yang ◽  
K.V. Shcheglov
Keyword(s):  
Room Temperature ◽  
Crystal Size ◽  
Initial Distribution ◽  
Engineering Control ◽  
Size Evolution ◽  
Silicon And Germanium ◽  
Ge Quantum Dot ◽  
And Control ◽  
Germanium Quantum Dots ◽  
Kinetics Of

Studies of the initial stages of nucleation of silicon and germanium have yielded insights that point the way to achievement of engineering control over crystal size evolution at the nanometer scale. In addition to their importance in understanding fundamental issues in nucleation, these studies are relevant to efforts to (i) control the size distributions of silicon and germanium “quantum dots𠇍, which will in turn enable control of the optical properties of these materials, (ii) and control the kinetics of crystallization of amorphous silicon and germanium films on amorphous insulating substrates so as to, e.g., produce crystalline grains of essentially arbitrary size.Ge quantum dot nanocrystals with average sizes between 2 nm and 9 nm were formed by room temperature ion implantation into SiO2, followed by precipitation during thermal anneals at temperatures between 30°C and 1200°C[1]. Surprisingly, it was found that Ge nanocrystal nucleation occurs at room temperature as shown in Fig. 1, and that subsequent microstructural evolution occurred via coarsening of the initial distribution.

Electron paramagnetic resonance in silicon and germanium

1964 ◽  
Vol 83 (7) ◽  
pp. 433-502 ◽  
Author(s):  
L.D. Bogomolova ◽  
V.N. Lazukin ◽  
I.V. Chepeleva
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Paramagnetic Resonance ◽  
Silicon And Germanium ◽  
Electron Paramagnetic

Hydrogen passivation of defect levels in the annealed CdZnTe:In crystals

2020 ◽  
Vol 35 (22) ◽  
pp. 3041-3047
Author(s):  
Lingyan Xu ◽  
Yan Zhou ◽  
Xu Fu ◽  
Lu Liang ◽  
Wanqi Jie
Keyword(s):  
Hydrogen Passivation ◽  
Defect Levels

Abstract

Sign in / Sign up

Export Citation Format

Share Document