Optoelectronic Functionality of BiFeO₃–SrTiO₃ Interface

Abstract

One effective way to extend the functional degree of freedom for semiconductors is to introduce structural defects (e.g., surface or interface) and chemical defects as they commonly exist and modify the properties of the entity. Here, the optoelectronic properties of bismuth ferrite thin films and their tuning by the interface between the film and the strontium titanate substrate are reported. The defects that have been demonstrated, especially oxygen vacancies, are of paramount importance in the photoelectric properties of a film‐substrate system. A detailed analysis of the oxygen vacancy levels supports the role of the interface in carrier transport. These results provide a new strategy to design the optoelectronic device via usual defect doping and interface coupling.

Boosting the Photocurrent in BiFeO3 Thin Films via a Domain‐Wall‐Defect Interaction

“…However, for the stripe domain thin film, J b first increases to about 225-250 K, and then decrease, remarkably differs from the behavior of monodomain BFO thin films. This hints that the origin of the photocurrent background of stripe domain structure might be related to the interplay between the defecttrap levels with the quasi-Fermi level shifting due to the temperature varying as we have previously shown [18,19] In this regard, we measured the photocurrent growth-decay behavior aiming to explore recombination and trapping effects as this is the fingerprint of the defect-trap levels. The experimental setup is schematically shown in Figure 2a, the details of which can be referred to the ref.…”

“…A time‐ and temperature‐dependent reducing H 2 or oxidizing O 2 atmosphere annealing treatment was specifically introduced to increase and decrease the density of oxygen vacancies, respectively. [ 18 ] The detail of each annealing process is given in Table 1 .…”

“…We focus on the behavior of the bulk photovoltaic effect of BFO thin films featuring different domain structures here. To rule out the potential contribution from the substrates in the optoelectronic property, [ 18 ] we grew BFO thin films on different substrates and subsequently measured their photoelectronic properties. The growth conditions are detailed in the Experimental Section.…”

Dynamic Control of Piezoelectricity Enhancement via Modulation of the Bulk Photovoltaic Effect in a BiFeO3 Thin Film

“…Further details of the BFO/STO growth and treatment conditions can be found in the recently published report. [30] Top Electrode Fabrication: Classical photolithography process was used to structure rectangular DC sputtered ≈60 nm Au electrode pairs (900 × 600 µm) on the top of BFO thin films. The spacing of the electrode pairs was ranging from 10 to 200 µm.…”

“…[29] Under illumination, the photoinduced charge carriers initially reach an equilibrium state and fill the levels located under the Fermi level. [28,30] After switching off the light, apart from the direct recombination process, the trapped charge carriers are gradually re-emitted, leading to the prolonged decay time through a de-trapping process. This should be responsible for the persistent behavior of enhanced PFM amplitude signals.…”