Theory of core excitons

Hjalmarson, Harold P.; Büttner, H.; Dow, John D.

doi:10.1103/physrevb.24.6010

Cited by 111 publications

(30 citation statements)

References 23 publications

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“…The changes of the intensity of the main peaks in the O K-edge spectrum (Figure 4 c), calculated in Z + 1 approximation (to account for the core-hole effects), [ 32,33 ] are similar to those observed in our XAS spectra, if only the contribution from the O atoms in close vicinity to the defect is taken into account (blue line on Figure 4 c): the intensity of peaks A and B 2 is somewhat decreased, while that of peak B 1 is increased as compared to the corresponding peaks in STO. While not vanishing completely, peak C is essentially suppressed.…”

Section: Ab Initio Calculations Of the Defect Structurementioning

confidence: 99%

Formation and Movement of Cationic Defects During Forming and Resistive Switching in SrTiO₃ Thin Film Devices

Lenser

Koehl

Slipukhina

et al. 2015

Adv Funct Materials

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Section: Ab Initio Calculations Of the Defect Structurementioning

confidence: 99%

Formation and Movement of Cationic Defects During Forming and Resistive Switching in SrTiO₃ Thin Film Devices

Lenser

Koehl

Slipukhina

et al. 2015

Adv Funct Materials

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“…4) 6,26 , resulting in a q-dependence much narrower than the experimental data. The failure of this calculation suggests a deeply-bound Frenkel-type exciton 8 , which would provide a broader final momentum distribution.…”

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confidence: 99%

Exciton spectroscopy of hexagonal boron nitride using nonresonant x-ray Raman scattering

et al. 2008

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We report non-resonant x-ray Raman scattering (XRS) measurements from hexagonal boron nitride for transferred momentum from 2 to 9Å −1 along directions both in and out of the basal plane. A symmetry-based argument, together with real-space full multiple scattering calculations of the projected density of states in the spherical harmonics basis, reveals that a strong pre-edge feature is a dominantly Y10-type Frenkel exciton with no other s-, p-, or d -components. This conclusion is supported by a second, independent calculation of the q-dependent XRS cross-section based on the Bethe-Salpeter equation. The physics of low-energy photoelectrons in solids is a complex, many body problem 1 . All aspects of the electronic structure of the material must be taken into account 2,3 , including the interaction between the photoelectron and the complementary hole 3,4,5,6 . This latter effect allows for similar long-lived bound states in metals (generally called Fermi-edge singularities) 7 and in insulators (called excitons) 8 . As a canonical example of a many body problem in condensed matter physics, core-excitons are a topic of continuing interest 4,5,6 .The present synergy between steadily progressing ab initio theoretical treatments 2,3,9,10 and on-going improvements in instrumentation 11 in studies of nonresonant x-ray Raman scattering (XRS) shows a strong potential for rapid progress on this old problem 5,6 . XRS is the inelastic scattering of hard x-rays from bound electrons, and XRS studies have seen a recent explosion in the number and range of applications 5,6,11,12,13,14,15,16,17 . In comparison with q-resolved electron energy loss spectroscopy (EELS) 18 , XRS is more suited for bulk condensed matter systems 13 due to the large penetration length afforded by the relative high-energy incident and scattered photons. The measured q-dependent XRS provides direct information about multipole contributions to the dynamic structure factor S(q, ω) 5,6,14,15,16 . It can be directly compared with theoretical calculations of S(q, ω) 6,14,15,16 , and can in some cases be inverted to provide an experimental measure of the perturbed projected density of states (l -DOS) 10,19 , which can again be compared to theory.XRS has shown itself to be especially suitable for spectroscopy of the angular characteristics of core excitons at the near edge region. For example, XRS studies 5,6 on LiF and icosahedral B 4 C convincingly demonstrated s-, and p-type excitons at the F and B K-edges, respectively, which can be attributed to atoms located at a center of inversion symmetry of the unit cell with parity a good quantum number for the final states 6 . Here, we demonstrate that for some systems one can learn not only the ∆l selection rule for the exciton but also a full description of its angular characteristics in terms of spherical harmonics, Y lm .We present measurements of the q-dependent XRS of hexagonal boron nitride (h-BN), an anisotropic system with all atoms sitting at positions with reflection symmetry to the basal plane (Figure 1,...

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“…In this class of alloys, lattice matching restricts us to materials with 32::::; { Z) ::::; 50. These are especially interesting materials because Sn has a zero band gap. The band gaps are predicted to be zero for the metastable alloys {!t;..\Sh _ _.Sn:u and (lnSb) 1 _ _.Sn:.x for all compositions (despite the fact that the equilibrium compounds lnAs and InSb have nonzero gaps 24 ). All of the Sn-based metastable alloys (with small lattice mismatches) mentioned above are either dirxt-gap or zero-gap materials.…”

Section: Hi Resultsmentioning

confidence: 99%

“…A. Harrison, Electronic Structurl' and the Properties .of Solids (Freeman, San Francisco, 1980 Surface core excitons are similar to surface defect states, as can be seen by using the optical alchemy approximation [23] or the Z+l rule [24].…”

Section: Ecmentioning

confidence: 99%

Scanning Tunneling Microscopy

Dow¹

1992

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REPORT DOCUMENTATION PAGE A' t> A J.Vq ~loJ-Form Approved OMB No. 0704·0188Puc11c recorrmg burCIttno aata sourc~. gatllertng anCI marnuuntng tl'le data nee<~eO Htghway, Suote 1204. Arlington. VI>. 22202-4302. and to tile Off•ceof Management ana BUdget, Pacerwor~ Reauctton PrOJ!Kt(0704-Q 188), Wasntngton. OC .<0503. Approved for public release; distribution unlimited. AGENCY USE ONLY (Leave blank) ,2. REPORT DATE ,3. REPORT TYPE AND OATES COVERED ABSTRACT (Maximum 200 words)Scanning tunneling microscopy (STM) has been used to image and modify the surfaces of III-V, II-VI artd group IV semiconductors. A tip-simulator basad on a photodcode was C:ieveloped. The simulator allows the development of ultra-sensitive electronics for controlling STM tip movement. Various forms of "nano-maching," including chiselling, sanding, and sweeping of atoms on a surface, were developed. An STM design was modified to allow bending of long thin samples of Sf(lOO) in UHV to permit the study of surfact strain. A variety of studies were conducted on Au(in air) CdTe (in air), Hg1-xMnxTe (under glycerin), and Hg 1-xCdx Te (in air and nnder glycerin). ReportDuring the course of this project, our group has accomplished the following "firsts": (1) The first scanning tunneling microscopy (STM) images of the InSb, InAs, and InP (110) 87-89 (1985).146. C. S. Lent, M. A. Bowen, J. D. Dow, R. S. Allgaier, 0. F. Sankey, and E. S. Ho.Relativistic empirical tight-binding theory of the energy bands of GeTe, SnTe, PbTe, PbSe, PbS, and their alloys.Superlatt. Microstruct. £, 491-499 (1986 2070-2073 (1984).167. J. D. Dow, R. E. Allen, and 0. F. Sankey. Intrinsic and extrinsic surface electronic states of semiconductors.Chem. and Phys. of Solid Surfaces, y, 483-500 (1984), ed. by R. Vanselow and R. Howe, Springer Series in Chemical Physics 35, (Springer-Verlag, Berlin, Heidelberg, New York, Tokyo).171. 0. F. Sankey, R. E. Allen, and J. D. Dow. Theory of Si/transition-metal silicide Schottky barriers. J. Ultramicroscopy 14, 127-130 (1984).172. 0. F. Sankey, R. E. Allen, and J. D. Dow. Theory of Schottky barrier formation for transition metals on Si, diamond, Ge, and SixGel-x alloys. J. page 4Vac. Sci. Technol. B~, 491-495 (1984).176. S. Lee, J. Sanchez-Dehesa, and J. D. Dow. Theoretical the pressure dependences of energy gaps in semiconductors. 1152-1155 (1985); ! 33, 7309 (1986 183. D W. Jenkin! K. E. Newman, and J. D. Dow. Predicted energy band gaps of (A1IIBV)l-x(X V) 2 x metastable, substitutional, crystalline alloys. Phys. Rev. B 32, 4034-4041 (1985).185. J. D. Dow, 0. F. Sankey, ...

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Theory of core excitons

Cited by 111 publications

References 23 publications

Formation and Movement of Cationic Defects During Forming and Resistive Switching in SrTiO₃ Thin Film Devices

Formation and Movement of Cationic Defects During Forming and Resistive Switching in SrTiO₃ Thin Film Devices

Exciton spectroscopy of hexagonal boron nitride using nonresonant x-ray Raman scattering

Scanning Tunneling Microscopy

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Theory of core excitons

Cited by 111 publications

References 23 publications

Formation and Movement of Cationic Defects During Forming and Resistive Switching in SrTiO3 Thin Film Devices

Formation and Movement of Cationic Defects During Forming and Resistive Switching in SrTiO3 Thin Film Devices

Exciton spectroscopy of hexagonal boron nitride using nonresonant x-ray Raman scattering

Scanning Tunneling Microscopy

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Product

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Formation and Movement of Cationic Defects During Forming and Resistive Switching in SrTiO₃ Thin Film Devices

Formation and Movement of Cationic Defects During Forming and Resistive Switching in SrTiO₃ Thin Film Devices