First-principles calculation of intrinsic defect formation volumes in silicon

Centoni, Scott A.; Sadigh, Babak; Gilmer, George H.; Lenosky, Thomas J.; Rubia, T. Dı́az de la; Musgrave, Charles B.

doi:10.1103/physrevb.72.195206

Cited by 81 publications

(49 citation statements)

References 31 publications

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“…The former relaxation volume calculated as the change in total volume of the defect supercell is -24.1Å 3 in good agreement with previous calculation [61,62]. The relaxation volume varies only marginally in the range of supercell size considered in this study: from -22.8Å…”

Section: Vibrational Formation Entropysupporting

confidence: 91%

“…Upon volume change, the phonon frequency for LA and TA modes are very slightly downshifted resulting in a decrease of c by less than 1% in agreement with the observed softening of the acoustic modes and decrease of the speed of sound. The observed discrepancies between the direct analysis of Δg(ω) and the elastic constant analysis can be attributed to (i) numerical error in estimating both speed of sound and defect strain polarizabilities [64], (ii) the difficulty to correctly describe this frequency region due to use of FP approach for a system with relatively flat energy landscape [61], (iii) volume effect are also known to influence the phonon vibration spectrum [20]. Figure 8 shows the evolution of ΔS vib f as a function of T for the neutral silicon vacancy in the D 2d configuration together with the entropic contribution from the different frequency regions defined previously.…”

Section: Neutral Vacancy In the D 2d Configurationmentioning

confidence: 99%

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On the ab initio calculation of vibrational formation entropy of point defect: the case of the silicon vacancy

Seeberger

Vidal

2017

EPJ Photovolt.

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Formation entropy of point defects is one of the last crucial elements required to fully describe the temperature dependence of point defect formation. However, while many attempts have been made to compute them for very complicated systems, very few works have been carried out such as to assess the different effects of finite size effects and precision on such quantity. Large discrepancies can be found in the literature for a system as primitive as the silicon vacancy. In this work, we have proposed a systematic study of formation entropy for silicon vacancy in its 3 stable charge states: neutral, +2 and -2 for supercells with size not below 432 atoms. Rationalization of the formation entropy is presented, highlighting importance of finite size error and the difficulty to compute such quantities due to high numerical requirement. It is proposed that the direct calculation of formation entropy of VSi using first principles methods will be plagued by very high computational workload (or large numerical errors) and finite size dependent results.

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Section: Vibrational Formation Entropysupporting

confidence: 91%

Section: Neutral Vacancy In the D 2d Configurationmentioning

confidence: 99%

On the ab initio calculation of vibrational formation entropy of point defect: the case of the silicon vacancy

Seeberger

Vidal

2017

EPJ Photovolt.

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“…For example, our data show that as the annealing conditions became more oxidizing, the measured c -axis for strained films increased, especially for tensile-strained films; the increase resulted from the filling of oxygen vacancies formed during the growth and/or the creation of oxygen interstitials. Calculations of the volume relaxation tensor 30 under unstrained conditions for these defects (Supplementary Table 3) demonstrated that interstitials (both oxide and peroxide) resulted in c axis lattice expansion ( V cc > 0), whereas both apical and equatorial oxygen vacancies resulted in c -axis lattice contraction ( V cc < 0) (Supplementary Note 2). Therefore, in progressing from reducing to oxidizing conditions, we expect a loss of vacancies or gain of interstitials to result in lattice expansion.…”

Section: Resultsmentioning

confidence: 99%

Strain control of oxygen kinetics in the Ruddlesden-Popper oxide La1.85Sr0.15CuO4

et al. 2018

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Oxygen defect control has long been considered an important route to functionalizing complex oxide films. However, the nature of oxygen defects in thin films is often not investigated beyond basic redox chemistry. One of the model examples for oxygen-defect studies is the layered Ruddlesden–Popper phase La2−xSrxCuO4−δ (LSCO), in which the superconducting transition temperature is highly sensitive to epitaxial strain. However, previous observations of strain-superconductivity coupling in LSCO thin films were mainly understood in terms of elastic contributions to mechanical buckling, with minimal consideration of kinetic or thermodynamic factors. Here, we report that the oxygen nonstoichiometry commonly reported for strained cuprates is mediated by the strain-modified surface exchange kinetics, rather than reduced thermodynamic oxygen formation energies. Remarkably, tensile-strained LSCO shows nearly an order of magnitude faster oxygen exchange rate than a compressively strained film, providing a strategy for developing high-performance energy materials.

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“…It is well known that in crystalline silicon, a vacancy defect is a kind of important intrinsic point defect. * E-mail: shuyingzhong@163.com So far, lots of reports have been related with the mechanical and electronic properties of the vacancy defects in crystalline silicon, which mainly referred to the defects of monovacancy, divacancy and hexavacancy [8][9][10][11][12]. Generally, the simplest monovacancy plays a key role in self-diffusion and impurity diffusion.…”

Section: Introductionmentioning

confidence: 99%

First-principle calculations of effective mass of silicon crystal with vacancy defects

Zhong

Lei

2016

Materials Science-Poland

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The energy band structures and electron (hole) effective masses of perfect crystalline silicon and silicon with various vacancy defects are investigated by using the plane-wave pseudopotential method based on density functional theory. Our results show that the effect of monovacancy and divacancy on the energy band structure of crystalline silicon is primarily reflected in producing the gap states and the local states in valence band maximum. It also causes breaking the symmetry of energy bands resulting from the Jahn-Teller effect, while only producing the gap states for the crystalline silicon with hexavacancy ring. However, vacancy point defects could not essentially affect the effective masses that are derived from the native energy bands of crystalline silicon, except for the production of defect states. Simultaneously, the Jahn-Teller distortions only affect the gap states and the local states in valence band maximum, but do not change the symmetry of conduction band minimum and the nonlocal states in valence band maximum, thus the symmetry of the effective masses. In addition, we study the electron (hole) effective masses for the gap states and the local states in valence band maximum.

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First-principles calculation of intrinsic defect formation volumes in silicon

Cited by 81 publications

References 31 publications

On the ab initio calculation of vibrational formation entropy of point defect: the case of the silicon vacancy

On the ab initio calculation of vibrational formation entropy of point defect: the case of the silicon vacancy

Strain control of oxygen kinetics in the Ruddlesden-Popper oxide La1.85Sr0.15CuO4

First-principle calculations of effective mass of silicon crystal with vacancy defects

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