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Title: Chemical potential shift and gap-state formation in SrTiO{sub 3−δ} revealed by photoemission spectroscopy

Abstract

In this study, we report on investigations of the electronic structure of SrTiO{sub 3} annealed at temperature ranging between 550 and 840 °C in an ultrahigh vacuum. Annealing induced oxygen vacancies (O{sub vac}) impart considerable changes in the electronic structure of SrTiO{sub 3}. Using core-level photoemission spectroscopy, we have studied the chemical potential shift (Δμ) as a function of annealing temperature. The result shows that the chemical potential monotonously increases with electron doping in SrTiO{sub 3−δ}. The monotonous increase of the chemical potential rules out the existence of electronic phase separation in the sample. Using valence band photoemission, we have demonstrated the formation of a low density of states at the near Fermi level electronic spectrum of SrTiO{sub 3−δ}. The gap-states were observed by spectral weight transfer over a large energy scale of the stoichiometric band gap of SrTiO{sub 3} system leading finally to an insulator-metal transition. We have interpreted our results from the point of structural distortions induced by oxygen vacancies.

Authors:
; ; ; ;  [1]
  1. CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India)
Publication Date:
OSTI Identifier:
22314549
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 5; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANNEALING; ELECTRONIC STRUCTURE; FERMI LEVEL; METALS; OXYGEN; PHOTOEMISSION; SPECTRA; SPECTROSCOPY; STOICHIOMETRY; STRONTIUM TITANATES; VACANCIES; VALENCE; WEIGHT

Citation Formats

Pal, Prabir, E-mail: palp@nplindia.org, Kumar, Pramod, Aswin, V., Dogra, Anjana, and Joshi, Amish G.. Chemical potential shift and gap-state formation in SrTiO{sub 3−δ} revealed by photoemission spectroscopy. United States: N. p., 2014. Web. doi:10.1063/1.4892397.
Pal, Prabir, E-mail: palp@nplindia.org, Kumar, Pramod, Aswin, V., Dogra, Anjana, & Joshi, Amish G.. Chemical potential shift and gap-state formation in SrTiO{sub 3−δ} revealed by photoemission spectroscopy. United States. doi:10.1063/1.4892397.
Pal, Prabir, E-mail: palp@nplindia.org, Kumar, Pramod, Aswin, V., Dogra, Anjana, and Joshi, Amish G.. Thu . "Chemical potential shift and gap-state formation in SrTiO{sub 3−δ} revealed by photoemission spectroscopy". United States. doi:10.1063/1.4892397.
@article{osti_22314549,
title = {Chemical potential shift and gap-state formation in SrTiO{sub 3−δ} revealed by photoemission spectroscopy},
author = {Pal, Prabir, E-mail: palp@nplindia.org and Kumar, Pramod and Aswin, V. and Dogra, Anjana and Joshi, Amish G.},
abstractNote = {In this study, we report on investigations of the electronic structure of SrTiO{sub 3} annealed at temperature ranging between 550 and 840 °C in an ultrahigh vacuum. Annealing induced oxygen vacancies (O{sub vac}) impart considerable changes in the electronic structure of SrTiO{sub 3}. Using core-level photoemission spectroscopy, we have studied the chemical potential shift (Δμ) as a function of annealing temperature. The result shows that the chemical potential monotonously increases with electron doping in SrTiO{sub 3−δ}. The monotonous increase of the chemical potential rules out the existence of electronic phase separation in the sample. Using valence band photoemission, we have demonstrated the formation of a low density of states at the near Fermi level electronic spectrum of SrTiO{sub 3−δ}. The gap-states were observed by spectral weight transfer over a large energy scale of the stoichiometric band gap of SrTiO{sub 3} system leading finally to an insulator-metal transition. We have interpreted our results from the point of structural distortions induced by oxygen vacancies.},
doi = {10.1063/1.4892397},
journal = {Journal of Applied Physics},
number = 5,
volume = 116,
place = {United States},
year = {Thu Aug 07 00:00:00 EDT 2014},
month = {Thu Aug 07 00:00:00 EDT 2014}
}