| 21. |
- Gali, Adam, et al.
(författare)
-
Correlation between the antisite pair and the D-I center in SiC
- 2003
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 67:15
-
Tidskriftsartikel (refereegranskat)abstract
- The D-I low temperature photoluminescence center is a well-known defect stable up to 1700 degreesC annealing in SiC, still its structure is not yet known. Combining experimental and theoretical studies, in this paper we will show that the properties of an antisite pair can reproduce the measured one-electron level position and local vibration modes of the D-I center, and are consistent with other experimental findings as well. We give theoretical values of the hyperfine constants of the antisite pair in its paramagnetic state as a means to confirm a model.
|
|
| 22. |
- Gali, Adam, et al.
(författare)
-
Hydrogen passivation of nitrogen in SiC
- 2003
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 83:7, s. 1385-1387
-
Tidskriftsartikel (refereegranskat)abstract
- A study is performed on hydrogen passivation of nitrogen in SiC. The first-principles calculations show that hydrogen may form stable complexes with substitutional nitrogen, passivating the shallow nitrogen donor. It is found that the complex is stable with respect to negatively charged hydrogen interstitials and isolated positive donors.
|
|
| 23. |
|
|
| 24. |
- Gali, Adam, et al.
(författare)
-
Overcoordinated hydrogens in the carbon vacancy : Donor centers of SiC
- 2000
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 84:21, s. 4926-4929
-
Tidskriftsartikel (refereegranskat)abstract
- Epitaxial silicon carbide is likely to contain hydrogen and vacancies (V), therefore, V + nH complexes are likely to influence its electronic properties. Using ob initio calculations we show that neutral and positive H atoms are trapped by carbon vacancies (V-C) in three-center bonds with two Si neighbors. The double positive charge state of V-C + H is not stable in equilibrium and in the triply positive state H binds only to one of the Si neighbors. At most two H atoms can be accommodated by a single V-C. The V-C + nH complexes have donor character and exhibit rather atypical vibration modes for Si-H bonds. Occupation levels and spin distributions were calculated and compared fur V-C + H and V-C.
|
|
| 25. |
- Gali, Ádám, et al.
(författare)
-
Point defects in SiC
- 2008
-
Konferensbidrag (refereegranskat)abstract
- Tight control of defects is pivotal for semiconductor technology. However, even the basic defects are not entirely understood in silicon carbide. In the recent years significant advances have been reached in the identification of defects by combining the experimental tools like electron paramagnetic resonance and photoluminescence with ab initio calculations. We summarize these results and their consequences in silicon carbide based technology. We show recent methodological developments making possible the accurate calculation of absorption and emission signals of defects.
|
|
| 26. |
- Gali, Adam, et al.
(författare)
-
Theoretical investigation of an intrinsic defect in SiC
- 2002
-
Ingår i: Materials Science Forum, Vols. 389-393. ; , s. 477-480
-
Konferensbidrag (refereegranskat)abstract
- Ab initio calculation of the local vibrational modes of a carbon pair in the silicon vacancy (V-Si+2C) shows that it cannot be the origin of the D-II photoluminescence (PL) center, however, it seems likely, that this defect gives rise to the Ramanpeaks observed at 1080 and 1435 cm(-1) in proton irradiated samples. Occupation levels of the V-Si+2C defect are also predicted to facilitate experimental confirmation.
|
|
| 27. |
|
|
| 28. |
- Gali, Adam, et al.
(författare)
-
Theory of Spin-Conserving Excitation of the N-V- Center in Diamond
- 2009
-
Ingår i: PHYSICAL REVIEW LETTERS. - 0031-9007. ; 103:18, s. 186404-
-
Tidskriftsartikel (refereegranskat)abstract
- The negatively charged nitrogen-vacancy defect in diamond is an important atomic-scale structure that can be used as a qubit in quantum computing and as a marker in biomedical applications. Its usefulness relies on the ability to optically excite electrons between well-defined gap states, which requires a clear and detailed understanding of the relevant states and excitation processes. Here we show that by using hybrid density-functional-theory calculations in a large supercell we can reproduce the zero-phonon line and the Stokes and anti-Stokes shifts, yielding a complete picture of the spin-conserving excitation of this defect.
|
|
| 29. |
- Gueorguiev Ivanov, Ivan, et al.
(författare)
-
Optical properties of the niobium centre in 4H, 6H, and 15R SiC
- 2013
-
Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2012. - : Trans Tech Publications. ; , s. 405-408
-
Konferensbidrag (refereegranskat)abstract
- A set of lines in the photoluminescence spectra of 4H-, 6H-, and 15R-SiC in the near-infrared are attributed to Nb-related defects on the ground of doping experiments conducted with 4H-SiC. A model based on a an exciton bound at the Nb-centre in an asymmetric split vacancy configuration at a hexagonal site is proposed, which explains the structure of the luminescence spectrum and the observed Zeeman splitting of the lines.
|
|
| 30. |
- Gulka, Michal, et al.
(författare)
-
Room-temperature control and electrical readout of individual nitrogen-vacancy nuclear spins
- 2021
-
Ingår i: Nature Communications. - : NATURE RESEARCH. - 2041-1723. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- Nuclear spins in semiconductors are leading candidates for future quantum technologies, including quantum computation, communication, and sensing. Nuclear spins in diamond are particularly attractive due to their long coherence time. With the nitrogen-vacancy (NV) centre, such nuclear qubits benefit from an auxiliary electronic qubit, which, at cryogenic temperatures, enables probabilistic entanglement mediated optically by photonic links. Here, we demonstrate a concept of a microelectronic quantum device at ambient conditions using diamond as wide bandgap semiconductor. The basic quantum processor unit - a single N-14 nuclear spin coupled to the NV electron - is read photoelectrically and thus operates in a manner compatible with nanoscale electronics. The underlying theory provides the key ingredients for photoelectric quantum gate operations and readout of nuclear qubit registers. This demonstration is, therefore, a step towards diamond quantum devices with a readout area limited by inter-electrode distance rather than by the diffraction limit. Such scalability could enable the development of electronic quantum processors based on the dipolar interaction of spin-qubits placed at nanoscopic proximity. Nuclear spins in diamond are promising for applications in quantum technologies due to their long coherence times. Here, the authors demonstrate a scalable electrical readout of individual intrinsic N-14 nuclear spins in diamond, mediated by hyperfine coupling to electron spin of the NV center, as a step towards room-temperature nanoscale diamond quantum devices.
|
|
