Temperature dependent spectroscopic studies of the electron delocalization dynamics of excited Ce ions in the wide band gap insulator, Lu2SiO5
Author(s) -
Erik van der Kolk,
S. A. Basun,
G. F. Imbusch,
W. M. Yen
Publication year - 2003
Publication title -
applied physics letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 442
eISSN - 1077-3118
pISSN - 0003-6951
DOI - 10.1063/1.1603337
Subject(s) - excited state , photocurrent , photoionization , ion , delocalized electron , band gap , photoconductivity , ionization , atomic physics , electron , materials science , quantum tunnelling , chemistry , molecular physics , optoelectronics , physics , organic chemistry , quantum mechanics
Electron delocalization processes of optically excited states of Ce3+ impurities in Lu2SiO5 were investigated by means of a temperature and spectrally resolved photoconductivity study. By monitoring separately the strength of the photocurrent resulting from excitation into each of the Ce3+?5d absorption bands, over a broad temperature region, three different delocalization processes, namely direct photoionization, thermal ionization, and tunneling, have been identified. The relative probabilities and temperature dependencies of each of these processes are discussed. The observed exponential temperature increase in the photocurrent, which spans six orders of magnitude, allows for the exact placement of the lowest energy 5d levels of the Ce3+ ions within the band gap. For Lu2SiO5:Ce3+, the lowest 5d state is determined to be 0.45 eV below the conduction band edge
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