<i>Ab initio</i><i>g</i> ‐tensor calculation for paramagnetic surface states: hydrogen adsorption at Si surfaces

Gerstmann, Uwe; Rohrmüller, Martin; Mauri, Francesco; Schmidt, Wolf Gero

doi:10.1002/pssc.200982462

Cited by 26 publications

(25 citation statements)

References 13 publications

(18 reference statements)

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“…Turning briefly to other spectroscopic techniques, first-principles calculations have been applied to the study of electron paramagnetic resonance (EPR) for example phosphorus defects at the Si-SiO 2 interface [74] and hydrogen vacancies on a silicon surface [75].…”

Section: Other Spectroscopiesmentioning

confidence: 99%

Density functional theory in the solid state

Hasnip

Refson

Probert

et al. 2014

Phil. Trans. R. Soc. A.

282

168

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Density functional theory (DFT) has been used in many fields of the physical sciences, but none so successfully as in the solid state. From its origins in condensed matter physics, it has expanded into materials science, high-pressure physics and mineralogy, solid-state chemistry and more, powering entire computational subdisciplines. Modern DFT simulation codes can calculate a vast range of structural, chemical, optical, spectroscopic, elastic, vibrational and thermodynamic phenomena. The ability to predict structure–property relationships has revolutionized experimental fields, such as vibrational and solid-state NMR spectroscopy, where it is the primary method to analyse and interpret experimental spectra. In semiconductor physics, great progress has been made in the electronic structure of bulk and defect states despite the severe challenges presented by the description of excited states. Studies are no longer restricted to known crystallographic structures. DFT is increasingly used as an exploratory tool for materials discovery and computational experiments, culminating in ex nihilo crystal structure prediction, which addresses the long-standing difficult problem of how to predict crystal structure polymorphs from nothing but a specified chemical composition. We present an overview of the capabilities of solid-state DFT simulations in all of these topics, illustrated with recent examples using the CASTEP computer program.

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Section: Other Spectroscopiesmentioning

confidence: 99%

Density functional theory in the solid state

Hasnip

Refson

Probert

et al. 2014

Phil. Trans. R. Soc. A.

282

168

View full text Add to dashboard Cite

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“…The EPR/ENDOR parameters are calculated in scalar-relativistic approximation using the gauge-including projector augmented plane wave (GI-PAW) approach [34] as implemented in the QUANTUM-ESPRESSO package [35]. For the g-tensor calculation spin-orbit coupling is taken into account in linear magnetic response, whereby the deviation of the elements of the g tensor from the free-electron value 2.002 319 can be described in a physically meaningful way by the spin currents j ( r) induced by the external magnetic field [24]. Note that at least 4 × 4 × 4 k-point samplings are necessary to obtain well converged elements of the electronic g tensor.…”

Section: Computationmentioning

confidence: 99%

“…Various paramagnetic defects have been evidenced in as-grown and irradiated samples but due to the lack of resolved hyperfine (hf) interaction and precise g-tensor measurements the so-called deep donor defects could not be identified. The only intrinsic defect clearly identified by magnetic resonance spectroscopy is the Ga interstitial [3]; it presents a very large central hf interaction which has been successfully modeled [24], whereas defects such as V Ga , V N , (V Ga -V N ), and N int have so far escaped clear identification. As ODMR measurements do not allow the determination of absolute defect concentrations their introduction rates could neither be established.…”

Section: Introductionmentioning

confidence: 99%

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Nitrogen split interstitial center(N−N)Nin GaN: High frequency EPR and ENDOR study

et al. 2014

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The nitrogen split interstitial defect introduced by high-energy particle irradiation in n-type GaN has been investigated by very high (up to 324 GHz) frequency electron paramagnetic resonance (EPR) and Q-band electron nuclear double resonance (ENDOR) spectroscopy. The increased resolution of the EPR spectra at 324 GHz has allowed us to determine the g-tensor anisotropy, which is not resolved at X or Q band. The good agreement of the principal values g xx = 1.9966, g yy = 2.0016, and g zz = 2.0036 with the theoretically predicted g tensor confirm the (N-N) N 0 defect model. The hyperfine interactions of this defect have been studied by Q-band ENDOR. We observed well-resolved ENDOR lines with distant Ga atoms from which the quadrupole coupling constants and the electrical field gradients were determined and discussed with the help of theoretical values. The observation of ENDOR spectra of the central N and Ga atoms predicted in the 20-90-MHz range required the use of field-frequency ENDOR due to the large linewidth of the ENDOR lines. Our results confirm the importance of the nitrogen split interstitial in particle irradiated GaN similar to the case of diamond and silicon carbide in which the stable configuration at room temperature of the carbon interstitials is also the split interstitial configuration.

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“…The g-tensor is computed by the GI-PAW formalism [11]. With these methods, EPR parameters can be reliably calculated [12,13]. The total energy of charged systems was corrected to account for supercell artifacts [14]; a representative value of 0.1 eV was chosen from test calculations.…”

Section: Electronic Structure Calculationsmentioning

confidence: 99%