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Photodynamics Study of KTaO3‑Based Conducting Interfaces

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journal contribution
posted on 21.01.2021, 09:30 by Saveena Goyal, Ruchi Tomar, Suvankar Chakraverty
The conducting interfaces of KTaO3 (KTO) with other appropriate oxides have recently received tremendous attention. These conducting electrons are not only two-dimensional in nature but also possess strong spin–orbit coupling (SOC). Here, we demonstrate the effect of light illumination on the transport properties of two recently discovered KTO’s based on two conducting interfaces: LaVO3–KTO (LVO–KTO) and EuO–KTO. Among these two samples, LVO–KTO is a conducting interface between two perovskite oxides. On the other hand, EuO–KTO is the conducting interface between a non-perovskite–perovskite oxide. A considerably large increase in conductivity upon laser light illumination (photoconductivity) as well as persistence of that conductivity even after the light is turned off (persistent photoconductivity (PPC)) are observed in both the samples. The overall photoconductivity switching behavior defined through the response characteristic of both the interfaces upon light illumination appears to be very similar and seems to be governed by KTO. Slightly larger photoconductivity as well as persistent current has been observed for the EuO–KTO interface in comparison to the LVO–KTO interface. The change in resistivity as a function of time under light illumination follows a biexponential behavior for both the interfaces. The relaxation time related to the fast component of this biexponential function is almost independent of wavelengths and the slow component decreases with increasing wavelengths of incident light. From the Laplace transform method, we have estimated the hole trap concentrations arising from the defect states, which are 5.77 × 1017 cm–2 for the EuO–KTO sample and 1.44 × 1019 cm–2 for the LVO–KTO sample.