The photoconductivity of an icosahedral quasicrystalline thin Al–Cu–Fe film obtained by magnetron sputtering was investigated. Pulsed photoconductivity measurements showed the presence of short-lived photoexcited charge carriers, the lifetime of which is on the order of several microseconds.
Modulated photoconductivity measured in the frequency range from 10 Hz to 10 kHz revealed the presence of deep levels in the forbidden zone that affect recombination processes. Analysis of the frequency dependence of photoconductivity allowed us to estimate the activation energy of these levels.
The obtained results indicate the complex structure of electronic states in quasicrystals and their influence on photoelectric properties. These data can be useful for the development of new optoelectronic devices based on quasicrystalline materials.
Pulsed and modulated photoconductivity were studied in an icosahedral Al–Cu–Fe quasicrystalline film. This study is the first report on the study of pulsed photoconductivity in quasicrystals. Application of both methods revealed photoconductivity with a wide spectrum of carrier relaxation times, varying from 10 to 100 s. Analysis of the obtained data shows that photoconductivity with a recombination time exceeding 10−3 s decreases with increasing temperature, while faster recombination is practically independent of temperature changes. Models simulating the frequency dependence of current and phase with direct and indirect excitation through localized states are used to interpret the modulated photoconductivity. The calculated results agree with the experimental data only when indirect excitation is taken into account. Analysis of the temperature dependence of the modulated photoconductivity indicates that the release of charge carriers from localized states is a process requiring thermal activation.Mn, it was possible to study the kinetics and location of formation of quantum dots.
Author: Kohei Soga, Yuzo Suzuki, Yosuke Kojima, Masatoshi Takeda, Kaoru Kimura
Institute: Department of Advanced Materials Science, Graduate School of Advanced Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Department of Mechanical Engineering, Nagaoka University of Technology, Kamito-myoka, Nagaoka, Niigata 940-2188, Japan