| 1. |
- Blumenau, A.T., et al.
(author)
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The effect of charge on kink migration at 90° partial dislocations in SiC
- 2005
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In: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 202:5, s. 877-882
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Journal article (peer-reviewed)abstract
- SiC bipolar devices show a degradation under forward-biased operation which has been linked with a recombination enhanced motion of one of the two glide dislocations having either Si or C core atoms. We have carried out calculations of the core structures and dynamics of partial dislocations in 3C and 2H-SiC using the density functional based codes DFTB and AIMPRO. After in earlier theoretical work we reported on the structure, energetics and electronic activity of both of the Shockley partials, and on the formation and migration barriers of kinks, in this work we present first results on the effect of charge on the disloction kinks. The calculations give insights into the device degradation mechanism.
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| 2. |
- Eberlein, T.A.G., et al.
(author)
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Alphabet luminescence lines in 4H-SiC
- 2002
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 65:18
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Journal article (peer-reviewed)abstract
- First-principles density functional calculations are used to investigate antisite pairs in 4H-SiC. We show that they are likely to be formed in close proximity under ionizing conditions, and they possess a donor level and thermal stability consistent with the series of 40 photoluminescent lines called the alphabet lines. Moreover, the gap vibrational mode of the silicon antisite defect is close to a phonon replica of the b1 line and possesses a weak isotopic shift with 13C in agreement with observation.
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| 3. |
- Eberlein, T.A.G., et al.
(author)
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Density functional theory calculation of the DI optical center in SiC
- 2006
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 74:14, s. 144106-1
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Journal article (peer-reviewed)abstract
- The DI center is a prominent defect which is detected in as-grown or irradiated SiC. It is unusual in that its intensity grows with heat treatments and survives anneals of 1700 °C. It has been assigned recently to either a close-by antisite pair or to the close-by antisite pair adjacent to a carbon antisite. We show here using local density functional calculations that these defects are not stable enough to account for DI. Instead, we assign DI to an isolated Si antisite and the four forms of the close-by antisite pair in 4H-SiC to the a, b, c, and d members of the alphabet series. The assignments allow us to understand the concentration of DI following growth, the recombination enhanced destruction of these alphabet defects and the annealing behavior of the remaining members of the series.
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| 4. |
- Eberlein, T.A.G., et al.
(author)
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Effect of charge on the movement of dislocations in SiC
- 2006
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 88:8, s. 82113-
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Journal article (peer-reviewed)abstract
- SiC bipolar devices show a degradation under forward-biased operation which has been linked with a current induced motion of one of the two glide dislocations having either Si or C core atoms. We have carried out calculations of the core structures and dynamics of partial dislocations in 3C and 2H-SiC. In this work we present results on the effect of charge on the dislocation kinks. The calculations show that silicon kinks have a deep filled band above the valence band and the trapping of holes into this band permits motion at room temperature.
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| 5. |
- Eberlein, T.A.G., et al.
(author)
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Grown-in and radiation-induced defects in 4H-SiC
- 2005
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In: Semiconductor defect engineering. - Warrendale, Pa : Materials Research Society. - 1558998179 ; , s. 3-13
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Conference paper (peer-reviewed)abstract
- SiC is a material that seems ideal for high-power, high frequency and high temperature electronic devices. It does not suffer from large reverse recovery inefficiencies typical for silicon when switching. In contrast to silicon. SiC is however difficult to dope by diffusion, and instead ion-implantation is used to achieve selective area doping. The drawback of this technique is that irradiating the crystal with dopant atoms creates a great, deal of lattice damage including vacancies, interstitials, antisites and impurity-radiation defect complexes. Although many of the point defects can be eliminated through thermal annealing, some however, e.g. the photoluminescence (PL) D1 and DLTS Z1/Z2 centers in 4H-SiC, are stable to high temperatures. In this polytype, D1 and the related alphabet lines are the most prominent PL signals. The latter can be seen directly after low energy irradiation while D1 usually dominates the PL spectrum of implanted and irradiated SiC after annealing. Not only implantation but also rapid growth of SiC by CVD methods leads to a deterioration in quality with an increase in electrically active grown in defects. Among these, the Z1/Z2 defects are dominant in n-type 4H-SiC. as well as material that has been exposed to radiation. We use first principles density functional calculations to investigate defect models for the above mentioned defects in 4H-SiC and relate their electrical and optical activity to experiments
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| 6. |
- Eberlein, T.A.G., et al.
(author)
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Movement and pinning of dislocations in SiC
- 2007
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In: Physica Status Solidi. C, Current topics in solid state physics. - : Wiley. - 1610-1634 .- 1610-1642. ; 4:8, s. 2923-2928
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Journal article (peer-reviewed)abstract
- SiC bipolar devices show a degradation under forward-biased operation due to the formation and rapid propagation of stacking faults in the active region of the device. It is believed that the observed rapid stacking fault growth is due to a recombination-enhanced dislocation glide (REDG) mechanism at the bordering partial dislocations having either Si or C core atoms. We investigated the effect of charge on the dislocation kinks and found that only silicon kinks have a deep filled band above the valence band. Trapping of holes into this band permits dislocation glide at room temperature. This mechanism is distinct from REDG as it requires only holes to be trapped at a Si partial and not in addition electrons in stacking fault states. We furthermore looked at the pinning of dislocations by nitrogen and boron and found a strong pinning of the C core by N and of the Si core by B.
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| 7. |
- Eberlein, T.A.G., et al.
(author)
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Self-interstitial clusters in silicon
- 2001
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In: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 308-310, s. 454-457
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Journal article (peer-reviewed)abstract
- Although there have been made many calculations for structures of the self-interstitial in Si and small aggregates of interstitials, In, there have been relatively few attempts to relate these defects with experimental data. Here, we discuss the assignments of the self-interstitial to the AA12 EPR centre and the di-interstitial to the P6 EPR centre.
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| 8. |
- Eberlein, T.A.G., et al.
(author)
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Shallow acceptors in GaN
- 2007
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 91:13, s. 132105-
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Journal article (peer-reviewed)abstract
- Recent high resolution photoluminescence studies of high quality Mg doped GaN show the presence of two acceptors. One is due to Mg and the other labeled A1 has a shallower acceptor defect. The authors investigate likely candidates for this shallow acceptor and conclude that CN is the most likely possibility. The authors also show that the CN is passivated by H and the passivated complex is more stable than MgGa-H
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| 9. |
- Fujita, N., et al.
(author)
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Theoretical aspects on the formation of the tri-interstitial nitrogen defect in silicon
- 2008
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In: Solid State Phenomena. - 1012-0394 .- 1662-9779. ; 131-133, s. 265-269
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Journal article (peer-reviewed)abstract
- In this paper we investigate the formation of interstitial nitrogen trimers N3 which have been suggested as a fast-diffusing species in silicon recently. Out-diffusion profiles of nitro-gen show the involvement of at least two independent nitrogen related defects in the diffusion process depending on the nitrogen concentration at different depths of the sample. When the nitrogen concentration is small it is proposed that nitrogen trimers are formed in a two step process. We present the structural properties of such a defect using density functional theory and examine the energetics of the two proposed reactions leading to the formation of N3.
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| 10. |
- Goss, J.P., et al.
(author)
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Electrical and optical properties of rod-like defects in silicon
- 2004
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 85:20, s. 4633-4635
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Journal article (peer-reviewed)abstract
- Self-interstitials in silicon can aggregate to form rod-like defects (RLDs) having both electrical and optical activity. We carry out local density functional calculations for both {113} and {111} RLDs to determine their structures and electrical activity. We find that small {113} RLDs are more stable than {111} RLDs but this reverses for larger defects. We attribute the electrical activity of {113} RLDs found in deep level transient spectroscopy studies with the bounding dislocations and the 0.903 eV photoluminescence to vacancy point defects lying on the habit plane.
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| 11. |
- Goss, J.P., et al.
(author)
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Planar interstitial aggregates in Si
- 2002
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In: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 14:48, s. 12843-12853
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Journal article (peer-reviewed)abstract
- Self-interstitials in silicon aggregate to form rod-like defects aligned along [110] directions and inhabiting either {111} or {113} crystallographic planes. These systems are known to be electrically and optically active. We present the results of first-principles calculations on the structure and energetics for candidate structures contained within the {113}, {111} and {001} planes and compare the results with experiment.
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| 12. |
- Jones, R., et al.
(author)
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Self-interstitial clusters in silicon
- 2002
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In: Nuclear Instruments and Methods in Physics Research Section B. - 0168-583X .- 1872-9584. ; 186:1, s. 10-18
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Journal article (peer-reviewed)abstract
- Although there have been many calculations of the structures of the self-interstitial in Si and small aggregates of interstititals, In, there has been little attempt to relate the defects with experimental data. Here we discuss the assignments of the self-interstitial to the AA12 electron paramagnetic resonance (EPR) centre, and the tri-interstitial and tetra-interstitial to the W-optical centre and the B3 EPR centre, respectively. Difficulties in the assignment of I2 to the P6 EPR centre are also noted.
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| 13. |
- Prezzi, D., et al.
(author)
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Hydrogen-related photoluminescent centers in SiC
- 2004
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 70:20, s. 205207-1
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Journal article (peer-reviewed)abstract
- Local density functional calculations are used to investigate models of the center responsible for a prominent set of luminescent lines with zero-phonon lines around 3.15 eV in hydrogen rich 4H-SiC and previously attributed to VSi-H . We find that the electronic structure of this defect and the character of its vibrational modes are inconsistent with this assignment. In contrast, a H2* center, bound to a carbon anti-site, is more stable than the isolated molecule and possesses a donor level close to that observed for the H-lines. Moreover, its vibrational modes are in good agreement with experiment. A possible mechanism for the radiation enhanced quenching of the defect is discussed.
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| 14. |
- Prezzi, D., et al.
(author)
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Optical and electrical properties of vanadium and erbium in 4H-SiC
- 2004
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 69:19, s. 193202-1
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Journal article (peer-reviewed)abstract
- Local-density-functional calculations are carried out on vanadium and erbium centers in 4H-SiC. Particular attention is paid to their electrical and optical properties. We find that both V and Er lie at Si sites and can exist in three charge states with deep donor and acceptor levels. While isolated VSi possesses intra-d and ionization induced optical transitions around 0.94 and 2.9 eV respectively, the intense and temperature stable intra-f optical transitions due to Er are unlikely to be due to an isolated Er defect. It is suggested that both impurities can trap H and N forming complexes which may limit the electrical efficiency of V and act as Er related exciton traps.
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