Electron trapping in the photo-induced conductivity decay in GaAs/SnO2 heterostructure

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de Freitas Bueno, Cristina [UNESP]
de Andrade Scalvi, Luis Vicente [UNESP]

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The decay of photo-induced conductivity is measured for GaAs/SnO2 heterostructure, after illumination with appropriate wavelength. The top oxide layer is deposited by sol–gel-dip-coating and doped with Eu3+, and the GaAs bottom layer is deposited by resistive evaporation. It shows quite unusual behavior since the decay rate gets slower as the temperature is raised. The trapping by intrabandgap defects in the SnO2 top layer is expected, but a GaAs/SnO2 interface arrest becomes also evident, mainly for temperatures below 100 K. Concerning the SnO2 layer, trapping by different defects is possible, due to the observed distinct capture time range. Besides Eu3+ centers and oxygen vacancies, this sort of heterostructure also leads to Eu3+ agglomerate areas in the SnO2 top layer surface, which may contribute for electron scattering. The electrical behavior reported here aims to contribute for the understanding of the electrical transport mechanisms which, combined with emission from Eu3+ ions from the top layer of the heterostructure, opens new possibilities for optoelectronic devices because samples in the form of films are desirable for circuit integration. The modeling of the photo-induced decay data yields the capture barrier in the range 620–660 meV, and contributes for the defect rules on the electrical properties of this heterostructure.



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Applied Physics A: Materials Science and Processing, v. 124, n. 6, 2018.