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arXiv · 1408.3516

Chemical potential shift and gap-state formation in SrTiO$_{3-δ}$ revealed by photoemission spectroscopy

Prabir Pal·Pramod Kumar·Aswin V.·Anjana Dogra·Amish G. Joshi
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Abstract

In this study, we report on investigations of the electronic structure of SrTiO$_3$ annealed at temperature ranging between 550 and 840$^\circ$C in an ultrahigh vacuum. Annealing induced oxygen vacancies (O$_{vac}$) impart considerable changes in the electronic structure of SrTiO$_3$. 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$_{3-δ}$. 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$_{3-δ}$. The gap-states were observed by spectral weight transfer over a large energy scale of the stoichiometric band gap of SrTiO$_3$ system leading finally to an insulator - metal transition. We have interpreted our results from the point of structural distortions induced by oxygen vacancies.

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Prabir Pal, Pramod Kumar, Aswin V., Anjana Dogra, Amish G. Joshi. 2014-08-15. Chemical potential shift and gap-state formation in SrTiO$_{3-δ}$ revealed by photoemission spectroscopy. https://doi.org/10.1063/1.4892397

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