4 research outputs found
Self-powered sensitive and stable UV-visible photodetector based on GdNiO3/Nb-doped SrTiO3 heterojunctions
The properties of perovskite nickelates are very sensitive to their oxygen content, which allows us to tune their electronic structures by varying the oxygen partial pressure during film deposition. Under the optimized condition, we have obtained GdNiO3 films that are sensitive to a wide spectrum of light. By combining the GdNiO3 film with Nb-doped SrTiO3 to form a heterojunction, we design a self-powered photodetector with high sensitivity toward light with a wavelength between 650 nm and 365 nm. Under 365 nm illumination (50 μW/cm2), the device shows a responsivity of 0.23 A/W at 0 V bias, comparable to or even better than the ultraviolet photodetectors made of semiconductor materials such as GaN or ZnO. The photo-dark ratio can be close to 103 when the power light density reaches 0.6 mW/cm2. Moreover, the device performance is very stable without any decay after 6 months.MOE (Min. of Education, S’pore)Published versio
Atomically engineered cobaltite layers for robust ferromagnetism
Emergent phenomena at heterointerfaces are directly associated with the
bonding geometry of adjacent layers. Effective control of accessible
parameters, such as the bond length and bonding angles, offers an elegant
method to tailor competing energies of the electronic and magnetic ground
states. In this study, we construct unit thick syntactic layers of cobaltites
within a strongly tilted octahedral matrix via atomically precise synthesis.
The octahedral tilt patterns of adjacent layers propagate into cobaltites,
leading to a continuation of octahedral tilting while maintaining significant
misfit tensile strain. These effects induce severe rumpling within an atomic
plane of neighboring layers triggers the electronic reconstruction between the
splitting orbitals. First-principles calculations reveal that the cobalt ions
transits to a higher spin state level upon octahedral tilting, resulting in
robust ferromagnetism in ultrathin cobaltites. This work demonstrates a design
methodology for fine-tuning the lattice and spin degrees of freedom in
correlated quantum heterostructures by exploiting epitaxial geometric
engineering.Comment: 18 pages, 5 figure