Berlin 2024 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 39: SrTiO3: A Versatile Material from Bulk Quantum Paraelectric to 2D Superconductor II (joint session TT/KFM/MA/O)
MA 39.4: Vortrag
Donnerstag, 21. März 2024, 15:45–16:00, H 0104
Dislocation-Induced Photoconductivity Enhancement in Fe-Doped SrTiO3: compensation of low mobility by high carrier density through the emergence of a sub-band gap level — •mehrzad soleimany1,2, till frömling1, jürgen rödel1, and marin alexe2 — 1Department of Materials and Earth Sciences, Technical University of Darmstadt, Darmstadt, Germany — 2Department of Physics, University of Warwick, Coventry, UK
Owing to the remarkable properties of SrTiO3 (STO), such as quantum paraelectric state below 37 K, negative differential resistance under illumination, and significant alteration of properties by doping, STO stands out among perovskite oxides. Until recently, little attention had been paid to the tunability of its properties - especially optical properties -via the introduction of dislocations. In this study, we introduce the method of dislocation imprint, which allows us to induce high densities of dislocations (> 1 x 1014 m−2) into a large volume of Fe-doped STO. Low-temperature I-V measurements indicated an about one order of magnitude increase in the photoconductivity of dislocation-rich samples. Photo-Hall measurements revealed that while dislocations might decrease the mobility, they could enhance the photoconductivity by increasing the number of carriers. Spectral responsivity measurements demonstrated that the higher carrier density could stem from the emergence of a sub-band gap level. Complementary C-AFM measurements conducted under illumination confirmed the local enhancement of photoconductivity at dislocations, which fitted well to the Electron Channeling Contrast Images of dislocations.
Keywords: Dislocation imprint; Photoconductivity; Photo-Hall measurment; Bandgap modification; Conductive Atomic Force Microscopy