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Proceedings Paper

Study of photoinduced charge transfer in SrTiO3: luminescence, photoconductivity and photo-EPR
Author(s): S. A. Basun; U. Bianchi; V. E. Bursian; Alexander A. Kaplyanskii; W. Kleemann; L. S. Sochava; V. S. Vikhnin
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Paper Abstract

A study of photoluminescence, photo-EPR, and of photoconductivity was carried out on SrTiO3 and Sr1-xCaxTiO3 (x equals 0.007) crystals containing a small amount of Cr. As a result, the location of Cr electronic levels in the band gap was found, Cr3+ being a donor located at 1.85 eV below the CB bottom and Cr4+ being an acceptor at 1.4 eV above the VB top. In accordance with this scheme, it was shown that: (1) Photons with energies exceeding 1.85 eV excite Cr3+ R luminescence in the course of the events; h(nu) exc + Cr3+ yields e + Cr4+ yields Cr3+(2E) + phonons yields Cr3+(4A2) + h(nu) R. (2) Excitation with photon energies above 1.4 eV converts Cr4+ to Cr$3+):h(nu) exc + Cr4+ yields h + Cr3+. (3) A band with low energy threshold at 2.1 eV is observed both in excitation spectra of R luminescence and of photoconductivity. The specific character of photoluminescence excitation manifests itself in a number of interesting observations: (i) Strong increase of steady-state R luminescence intensity under IR irradiation additional to excitation in the visible. (ii) IR induced transient R luminescence caused by previous irradiation in the visible. (iii) Very long tails on the time scale of 1000s in R luminescence decay with weak dependence on temperature from 2 K to 78 K.

Paper Details

Date Published: 3 January 1996
PDF: 10 pages
Proc. SPIE 2706, Tenth Feofilov Symposium on Spectroscopy of Crystals Activated by Rare-Earth and Transitional-Metal Ions, (3 January 1996); doi: 10.1117/12.229167
Show Author Affiliations
S. A. Basun, A.F. Ioffe Physico-Technical Institute (Russia)
U. Bianchi, Gerhard-Mercator-Univ. (Germany)
V. E. Bursian, A.F. Ioffe Physico-Technical Institute (Russia)
Alexander A. Kaplyanskii, A.F. Ioffe Physico-Technical Institute (Russia)
W. Kleemann, Gerhard-Mercator-Univ. (Germany)
L. S. Sochava, A.F. Ioffe Physico-Technical Institute (Russia)
V. S. Vikhnin, A.F. Ioffe Physico-Technical Institute (Russia)

Published in SPIE Proceedings Vol. 2706:
Tenth Feofilov Symposium on Spectroscopy of Crystals Activated by Rare-Earth and Transitional-Metal Ions
Alexander I. Ryskin; V. F. Masterov, Editor(s)

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