posted on 2023-01-03, 17:44authored byYoungki Yeo, Soo-Yoon Hwang, Jinwook Yeo, Jihun Kim, Jinhyuk Jang, Heung-Sik Park, Yong-Jin Kim, Duc Duy Le, Kyung Song, Moonhong Kim, Seunghwa Ryu, Si-Young Choi, Chan-Ho Yang
Mobile
defects in solid-state materials play a significant
role
in memristive switching and energy-efficient neuromorphic computation.
Techniques for confining and manipulating point defects may have great
promise for low-dimensional memories. Here, we report the spontaneous
gathering of oxygen vacancies at strain-relaxed crack walls in SrTiO3 thin films grown on DyScO3 substrates as a result
of flexoelectricity. We found that electronic conductance at the crack
walls was enhanced compared to the crack-free region, by a factor
of 104. A switchable asymmetric diode-like feature was
also observed, and the mechanism is discussed, based on the electrical
migration of oxygen vacancy donors in the background of Sr-deficient
acceptors forming n+–n or n–n+ junctions. By tracing
the temporal relaxations of surface potential and lattice expansion
of a formed region, we determine the diffusivity of mobile defects
in crack walls to be 1.4 × 10–16 cm2/s, which is consistent with oxygen vacancy kinetics.