In the wide range of temperature, 45K to 350K, the thermally stimulated currents in anthracene single crystals are measured by the new method, which we have proposed previously. In this paper, we discuss generally the shallow trapping centers which are observed between 45K and 220K (at heating rate β_??_0.06 K/sec).
Complicated curve of thermally stimulated currents, which consists of several peaks, can, be observed in this temperature range. These experimental results suggest a discrete, rather than a continuous, distribution of trapping centers. About ten of these trapping levels have been separated successfully through a thermal cleaning technique and their energy depths are valued at about 0.03_??_0.34 eV.
It is shown that the present results are not contradictory to the previously reported results, and furthermore, make it possible to advance a further step towards the understanding of trapping centers, because energy gaps not reported in previous results are covered by the present results.
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