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

Pulsed and modulated photoconductivity in icosahedral quasicrystalline Al–Cu–Fe thin films is an important aspect revealing the unique electrical and optical properties of such materials. Quasicrystals have a random structure, which contributes to the emergence of unusual transport properties. This paper discusses a technique for measuring photoconductivity based on short light pulses and modulated action using different frequencies.

Aluminum-based icosahedral (i-) quasicrystals exhibit unique characteristics such as i-cluster solids and aperiodic ordered structure. An i-QC is an elementary unit of an i-cluster consisting of 12 or 13 atoms. The properties of the material are determined by the electronic structure of the clusters and the types of bonds between them. The quasi-crystalline structure can be considered as a kind of transition between crystalline and amorphous materials, which leads to the emergence of intermediate properties, including electrical conductivity. Some i-QCs exhibit transport properties similar to semiconductors despite their metallic origin. A combination of metallic and covalent bonds is also observed. The unique semiconductor characteristics, including low electrical conductivity and temperature increase in charge density, are explained by the presence of a pseudogap in the electron density of states. In this work, we investigated the photoconductivity of i-Al–Cu–Fe QC thin film at different temperatures and discussed the influence of the interaction between photocarriers and localized states on the process of charge carrier generation and recombination.

Studies show that the photoconductivity of Al–Cu–Fe thin films depends on the wavelength of light and temperature, which is due to the features of energy levels and the localization of electrons in the quasi-crystalline lattice. Analysis of the obtained data allows us to identify the mechanisms of charge recombination and electron transfer, as well as to evaluate the effect of doping additives on photoconductivity.

The experimental results open up new prospects for the development of photonic devices and sensors based on quasi-crystalline materials, which facilitates further study of their potential application in modern technologies.

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