Nonstoichiometry and point defects in PbTe

Schenk, M.; Berger, H.; Klimakow, A.; Mühlberg, M.; Wienecke, M.

doi:10.1002/crat.2170230111

Cited by 24 publications

(23 citation statements)

References 23 publications

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“…34,37 However, in our results we find that only HSE + SOC + G 0 W 0 results correctly reproduce the experiments, without any experimental inputs. The n-type intrinsic behavior in GGA + SOC and GGA + SOC + GW is much more prominent than HSE + SOC, due to singularly dominating donor type Te 2þ Pb defect resulting in the equilibrium Fermi level close to the conduction band.…”

Section: Pb and Te 2þsupporting

confidence: 58%

“…The computed free carrier concentrations are within half to an order magnitude of the experimental values 34,36,37 depending on the temperature, as shown in Fig. 6c and d. HSE + SOC calculations without the G 0 W 0 band edge shifts, predict the correct n-type conductivity under Te-poor conditions, but fail to predict the p-type conductivity under Te-rich conditions at low temperatures.…”

Section: Te and Te 2þsupporting

confidence: 56%

“…34,55 Proposition of Pb interstitial as dominating defect over Te vacancies under Te-poor conditions has been made by Schenk et al, 37 and in an earlier work by Brebrick and Allgaier. 56 However, Brebrick and Grubner 34 later corrected their previous conclusions 56 by citing the presence of Cu impurities as donor in Te-poor conditions and not Pb interstitials.…”

Section: Pb and Te 2þmentioning

confidence: 84%

“…35,60 The experimental data in Fig. 6c and d is from Hall measurements [34][35][36][37] done between 77-100 K on quenched samples that are annealed at a much higher temperature range, between 400 and 1100 K. Therefore carrier concentrations from the charge neutrality condition (Eq. 3) are computed at 100 K, using defect concentrations corresponding to the annealing temperature of the experiment.…”

Section: Te and Te 2þmentioning

confidence: 99%

“…This is in contrast to experimentally-observed p-type conductivity under Te-rich conditions and n-type under Te-poor conditions. [34][35][36][37] Given the contested accuracy of defect calculations in compounds with strong spin-orbit coupling, this work focuses on PbTe to establish best practices in defect and dopability calculations. By using hybrid functionals (HSE stands for HSE06 38,39 ) along with spin-orbit coupling to perform defect calculations and quasi-particle GW approach (at G 0 W 0 level) to describe the valence and conduction band edges, we obtain (1) a quantitatively accurate description of the defect chemistry and associated free carrier concentrations in PbTe, and (2) bipolar doping behavior, in agreement with experiments.…”

Section: Introductionmentioning

confidence: 99%

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First-principles calculation of intrinsic defect chemistry and self-doping in PbTe

et al. 2017

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Semiconductor dopability is inherently limited by intrinsic defect chemistry. In many thermoelectric materials, narrow band gaps due to strong spin-orbit interactions make accurate atomic level predictions of intrinsic defect chemistry and self-doping computationally challenging. Here we use different levels of theory to model point defects in PbTe, and compare and contrast the results against each other and a large body of experimental data. We find that to accurately reproduce the intrinsic defect chemistry and known self-doping behavior of PbTe, it is essential to (a) go beyond the semi-local GGA approximation to density functional theory, (b) include spin-orbit coupling, and (c) utilize many-body GW theory to describe the positions of individual band edges. The hybrid HSE functional with spin-orbit coupling included, in combination with the band edge shifts from G 0 W 0 is the only approach that accurately captures both the intrinsic conductivity type of PbTe as function of synthesis conditions as well as the measured charge carrier concentrations, without the need for experimental inputs. Our results reaffirm the critical role of the position of individual band edges in defect calculations, and demonstrate that dopability can be accurately predicted in such challenging narrow band gap materials. INTRODUCTIONThe dopability of semiconductor materials plays a decisive role in device performance. Dopability refers to the carrier concentration limits achievable in a semiconductor material. These limits are set by the compensating intrinsic (or native) defects and the solubility of extrinsic dopants. The computational prediction of dopability has a multi-decade history in microelectronic and optoelectronic materials (e.g. III-V compounds, 1 transparent conducting oxides 2,3 ). Successful computational prediction of dopability has been enabled by the accurate description of native defect chemistry, their formation energies and the absolute position of band edges in these materials.

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Section: Pb and Te 2þsupporting

confidence: 58%

Section: Te and Te 2þsupporting

confidence: 56%

Section: Pb and Te 2þmentioning

confidence: 84%

Section: Te and Te 2þmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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First-principles calculation of intrinsic defect chemistry and self-doping in PbTe

et al. 2017

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Lattice parameter determination of superlattices

Berger

Rosner

Schikora

1989

Cryst. Res. Technol.

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A inethod for determination of absolute lattice parameters of superlattices is describedwhich does not use any relations to substrate reflections. For superlattices having tetragonal or trigonal symmetry, three parameters are to be determined. For this purpose, the diffraction angles of two reflections are measured, the third angle is obtained from the incidence angle difference of two single reflections of a "reflection group". The peak shift caused by partial superposition of the single reflections, which occurs a t larger superlattice periods, is corrected by means of simulation calculetions. As an example, the results obtained on a PbTe/(Pb, Sn)Te superlattice are given and discussed.Es wird eine Methode zur Absolutbestiiiiniuiig voii Superlattice-Gitterparametern beschrieben, die keiiien Bezug auf Substratreflexe niinmt. Fur tetragonal oder trigonal verzerrte Superlattice-Strukturen sind drei Parameter zu bestimmen. Dazu werden zwei Beugungswinkel geinessen, der dritte Winkel wird aus der Einfallswinkeldifferenz zweier Eiiizelreflexe einer ,,Reflexgruppe" ermittelt. Die Peakverschiebung durch teilweise Uberlagerung von Einzelreflexen, die bei grol3en Superlatticeperioden auftritt, wird mit Hilfe von Simulationsrechnungen korrigiert. Als Beispiel werden Ergebnisse an einem PbTe/(Pb, Sn)Te-Superlattice angegeben und diskutiert.

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X‐Ray Diffraction Studies on Point Defects in II–VI Compounds

Berger

1993

Cryst. Res. Technol.

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The point defect concentration in Te-rich CdTe and Hg, -,Cd,Te annealed at various temperatures has been estimated from precision lattice parameters using a simple continuum inclusion model and compared with densities of electrically charged defects determined by high-temperature Hall and conductivity measurements. The nonstoichiometry is realized by cation vacancies. Dependent on the CdTe content, the ratio of total to charged defect concentrations varies between about unity for HgTe-rich composition and 75 for CdTe. Therefore, it is necessary to distinct between "electrical" and "chemical" stability regions.In Te-reichem CdTe und Hg, -,Cd,Te wurden die durch Tempern bei verschiedenen Temperaturen eingestellten Punktdefektkonzentrationen aus Prazionsgitterkonstanten mit Hilfe eines einfachen Kontinuums-EinschluB-Modells abgeschatzt und mit der Dichte geladener Defekte, die durch Hochtemperatur-Hall-und -Leitfahigkeitsmessungen bestimmt wurde, verglichen. Die Nichtstochiometrie wird durch Kationenleerstellen realisiert. In Abhangigkeit von CdTe-Gehalt variiert das Verhaltnis der Konzentration der Gesamtzahl zu dem der geladenen Defekte zwischen annahernd eins fur HgTe-reiche Zusammensetzung und 75 fur CdTe. Es ist deshalb notwendig, zwischen ,,elektrischem" und ,,chemischem" Stabilitatsgebiet zu unterscheiden.

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Nonstoichiometry and point defects in PbTe

Cited by 24 publications

References 23 publications

First-principles calculation of intrinsic defect chemistry and self-doping in PbTe

First-principles calculation of intrinsic defect chemistry and self-doping in PbTe

Lattice parameter determination of superlattices

X‐Ray Diffraction Studies on Point Defects in II–VI Compounds

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