Conduction band-edge states associated with the removal of d-state degeneracies by the Jahn-Teller effect

Gerald Lucovsky, C. C. Fulton, Y. Zhang, Y. Zou, J. Luning, L. F. Edge, J. L. Whitten, Robert Nemanich, H. Ade, D. G. Schlom, V. V. Afanase'v, A. Stesmans, S. Zollner, D. Triyoso, B. R. Rogers

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

X-ray absorption spectroscopy (XAS) is used to study band edge electronic structure of high-κ transition metal (TM) and trivalent lanthanide rare earth (RE) oxide gate dielectrics. The lowest conduction band d* -states in TiO2, ZrO2 and HfO2 are correlated with: 1) features in the O K1 edge, and 2) transitions from occupied Ti 2p, Zr 3p and Hf 4p states to empty Ti 3d-, Zr 4d-, and Hf 5d-states, respectively. The relative energies of d-state features indicate that the respective optical bandgaps, Eopt (or equivalentiy, Eg), and conduction band offset energy with respect to Si, EB, scale monotonically with the d-state energies of the TM/RE atoms. The multiplicity of d-state features in the Ti L2,3 spectrum of TiO2, and in the derivative of the O K1 spectra for ZrO2 and HfO2 indicate a removal of d-state degeneracies that results from a static Jahn-Teller effect in these nanocrystalline thin film oxides. Similar removals of d-state degeneracies are demonstrated for complex TM/RE oxides including Zr and Hf titanates, and La, Gd and Dy scandates. Analysis of XAS and band edge spectra indicate an additional band edge state that is assigned Jahn-Teller distortions at internal grain boundaries. These band edges defect states are electronically active in photoconductivity (PC), internal photoemission (IPE), and act as bulk traps in metal oxide semiconductor (MOS) devices, contributing to asymmetries in tunneling and Frenkel-Poole transport that have important consequences for performance and reliability in advanced Si devices.

Original languageEnglish (US)
Pages (from-to)65-83
Number of pages19
JournalIEEE Transactions on Device and Materials Reliability
Volume5
Issue number1
DOIs
StatePublished - Mar 2005
Externally publishedYes

Fingerprint

Jahn-Teller effect
Rare Earth Metals
Conduction bands
Oxides
Rare earths
Transition metals
X ray absorption spectroscopy
Lanthanoid Series Elements
MOS devices
Gate dielectrics
Optical band gaps
Photoconductivity
Photoemission
Rare earth elements
Electron energy levels
Electronic structure
Absorption spectra
Grain boundaries
Derivatives
Thin films

Keywords

  • Complex oxides
  • Conduction band edge states
  • D-state degeneracy
  • High-κ dielectrics
  • Jahn-Teller splittings
  • Photoconductivity
  • Spectroscopic ellipsometry
  • X-ray absorption spectroscopy

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

Cite this

Conduction band-edge states associated with the removal of d-state degeneracies by the Jahn-Teller effect. / Lucovsky, Gerald; Fulton, C. C.; Zhang, Y.; Zou, Y.; Luning, J.; Edge, L. F.; Whitten, J. L.; Nemanich, Robert; Ade, H.; Schlom, D. G.; Afanase'v, V. V.; Stesmans, A.; Zollner, S.; Triyoso, D.; Rogers, B. R.

In: IEEE Transactions on Device and Materials Reliability, Vol. 5, No. 1, 03.2005, p. 65-83.

Research output: Contribution to journalArticle

Lucovsky, G, Fulton, CC, Zhang, Y, Zou, Y, Luning, J, Edge, LF, Whitten, JL, Nemanich, R, Ade, H, Schlom, DG, Afanase'v, VV, Stesmans, A, Zollner, S, Triyoso, D & Rogers, BR 2005, 'Conduction band-edge states associated with the removal of d-state degeneracies by the Jahn-Teller effect', IEEE Transactions on Device and Materials Reliability, vol. 5, no. 1, pp. 65-83. https://doi.org/10.1109/TDMR.2005.845804
Lucovsky, Gerald ; Fulton, C. C. ; Zhang, Y. ; Zou, Y. ; Luning, J. ; Edge, L. F. ; Whitten, J. L. ; Nemanich, Robert ; Ade, H. ; Schlom, D. G. ; Afanase'v, V. V. ; Stesmans, A. ; Zollner, S. ; Triyoso, D. ; Rogers, B. R. / Conduction band-edge states associated with the removal of d-state degeneracies by the Jahn-Teller effect. In: IEEE Transactions on Device and Materials Reliability. 2005 ; Vol. 5, No. 1. pp. 65-83.
@article{6240b446487347cbae8db6e9a257626e,
title = "Conduction band-edge states associated with the removal of d-state degeneracies by the Jahn-Teller effect",
abstract = "X-ray absorption spectroscopy (XAS) is used to study band edge electronic structure of high-κ transition metal (TM) and trivalent lanthanide rare earth (RE) oxide gate dielectrics. The lowest conduction band d* -states in TiO2, ZrO2 and HfO2 are correlated with: 1) features in the O K1 edge, and 2) transitions from occupied Ti 2p, Zr 3p and Hf 4p states to empty Ti 3d-, Zr 4d-, and Hf 5d-states, respectively. The relative energies of d-state features indicate that the respective optical bandgaps, Eopt (or equivalentiy, Eg), and conduction band offset energy with respect to Si, EB, scale monotonically with the d-state energies of the TM/RE atoms. The multiplicity of d-state features in the Ti L2,3 spectrum of TiO2, and in the derivative of the O K1 spectra for ZrO2 and HfO2 indicate a removal of d-state degeneracies that results from a static Jahn-Teller effect in these nanocrystalline thin film oxides. Similar removals of d-state degeneracies are demonstrated for complex TM/RE oxides including Zr and Hf titanates, and La, Gd and Dy scandates. Analysis of XAS and band edge spectra indicate an additional band edge state that is assigned Jahn-Teller distortions at internal grain boundaries. These band edges defect states are electronically active in photoconductivity (PC), internal photoemission (IPE), and act as bulk traps in metal oxide semiconductor (MOS) devices, contributing to asymmetries in tunneling and Frenkel-Poole transport that have important consequences for performance and reliability in advanced Si devices.",
keywords = "Complex oxides, Conduction band edge states, D-state degeneracy, High-κ dielectrics, Jahn-Teller splittings, Photoconductivity, Spectroscopic ellipsometry, X-ray absorption spectroscopy",
author = "Gerald Lucovsky and Fulton, {C. C.} and Y. Zhang and Y. Zou and J. Luning and Edge, {L. F.} and Whitten, {J. L.} and Robert Nemanich and H. Ade and Schlom, {D. G.} and Afanase'v, {V. V.} and A. Stesmans and S. Zollner and D. Triyoso and Rogers, {B. R.}",
year = "2005",
month = "3",
doi = "10.1109/TDMR.2005.845804",
language = "English (US)",
volume = "5",
pages = "65--83",
journal = "IEEE Transactions on Device and Materials Reliability",
issn = "1530-4388",
publisher = "Institute of Electrical and Electronics Engineers Inc.",
number = "1",

}

TY - JOUR

T1 - Conduction band-edge states associated with the removal of d-state degeneracies by the Jahn-Teller effect

AU - Lucovsky, Gerald

AU - Fulton, C. C.

AU - Zhang, Y.

AU - Zou, Y.

AU - Luning, J.

AU - Edge, L. F.

AU - Whitten, J. L.

AU - Nemanich, Robert

AU - Ade, H.

AU - Schlom, D. G.

AU - Afanase'v, V. V.

AU - Stesmans, A.

AU - Zollner, S.

AU - Triyoso, D.

AU - Rogers, B. R.

PY - 2005/3

Y1 - 2005/3

N2 - X-ray absorption spectroscopy (XAS) is used to study band edge electronic structure of high-κ transition metal (TM) and trivalent lanthanide rare earth (RE) oxide gate dielectrics. The lowest conduction band d* -states in TiO2, ZrO2 and HfO2 are correlated with: 1) features in the O K1 edge, and 2) transitions from occupied Ti 2p, Zr 3p and Hf 4p states to empty Ti 3d-, Zr 4d-, and Hf 5d-states, respectively. The relative energies of d-state features indicate that the respective optical bandgaps, Eopt (or equivalentiy, Eg), and conduction band offset energy with respect to Si, EB, scale monotonically with the d-state energies of the TM/RE atoms. The multiplicity of d-state features in the Ti L2,3 spectrum of TiO2, and in the derivative of the O K1 spectra for ZrO2 and HfO2 indicate a removal of d-state degeneracies that results from a static Jahn-Teller effect in these nanocrystalline thin film oxides. Similar removals of d-state degeneracies are demonstrated for complex TM/RE oxides including Zr and Hf titanates, and La, Gd and Dy scandates. Analysis of XAS and band edge spectra indicate an additional band edge state that is assigned Jahn-Teller distortions at internal grain boundaries. These band edges defect states are electronically active in photoconductivity (PC), internal photoemission (IPE), and act as bulk traps in metal oxide semiconductor (MOS) devices, contributing to asymmetries in tunneling and Frenkel-Poole transport that have important consequences for performance and reliability in advanced Si devices.

AB - X-ray absorption spectroscopy (XAS) is used to study band edge electronic structure of high-κ transition metal (TM) and trivalent lanthanide rare earth (RE) oxide gate dielectrics. The lowest conduction band d* -states in TiO2, ZrO2 and HfO2 are correlated with: 1) features in the O K1 edge, and 2) transitions from occupied Ti 2p, Zr 3p and Hf 4p states to empty Ti 3d-, Zr 4d-, and Hf 5d-states, respectively. The relative energies of d-state features indicate that the respective optical bandgaps, Eopt (or equivalentiy, Eg), and conduction band offset energy with respect to Si, EB, scale monotonically with the d-state energies of the TM/RE atoms. The multiplicity of d-state features in the Ti L2,3 spectrum of TiO2, and in the derivative of the O K1 spectra for ZrO2 and HfO2 indicate a removal of d-state degeneracies that results from a static Jahn-Teller effect in these nanocrystalline thin film oxides. Similar removals of d-state degeneracies are demonstrated for complex TM/RE oxides including Zr and Hf titanates, and La, Gd and Dy scandates. Analysis of XAS and band edge spectra indicate an additional band edge state that is assigned Jahn-Teller distortions at internal grain boundaries. These band edges defect states are electronically active in photoconductivity (PC), internal photoemission (IPE), and act as bulk traps in metal oxide semiconductor (MOS) devices, contributing to asymmetries in tunneling and Frenkel-Poole transport that have important consequences for performance and reliability in advanced Si devices.

KW - Complex oxides

KW - Conduction band edge states

KW - D-state degeneracy

KW - High-κ dielectrics

KW - Jahn-Teller splittings

KW - Photoconductivity

KW - Spectroscopic ellipsometry

KW - X-ray absorption spectroscopy

UR - http://www.scopus.com/inward/record.url?scp=20444477165&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=20444477165&partnerID=8YFLogxK

U2 - 10.1109/TDMR.2005.845804

DO - 10.1109/TDMR.2005.845804

M3 - Article

VL - 5

SP - 65

EP - 83

JO - IEEE Transactions on Device and Materials Reliability

JF - IEEE Transactions on Device and Materials Reliability

SN - 1530-4388

IS - 1

ER -