Browsing by Author "Pan, Xiao-Qing"

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Giant Photoresponse in Quantized SrRuO3 Monolayer at Oxide Interfaces
(2018-03-01)
Liu, Heng-Jui
;
Wang, Jing-Ching
;
Cho, Deok-Yong
;
Ho, Kang-Ting
;
Lin, Jheng-Cyuan
The photoelectric effect in semiconductors is the main mechanism for most modern optoelectronic devices, in which the adequate bandgap plays the key role for acquiring high photoresponse. Among numerous material categories applied in this field, the complex oxides exhibit great possibilities because they present a wide distribution of band gaps for absorbing light with any wavelength. Their physical properties and lattice structures are always strongly coupled and sensitive to light illumination. Moreover, the confinement of dimensionality of the complex oxides in the heterostructures can provide more diversities in designing and modulating the band structures. On the basis of this perspective, we have chosen itinerary ferromagnetic SrRuO3 as the model material, and fabricated it in one-unit-cell thickness in order to open a small band gap for effective utilization of visible light. By inserting this SrRuO3 monolayer at the interface of the well-developed two-dimensional electron gas system (LaAlO3/SrTiO3), the resistance of the monolayer can be further revealed. In addition, a giant enhancement (>300%) of photoresponse under illumination of visible light with power density of 500 mW/cm(2) is also observed. Such can be ascribed to the further modulation of band structure of the SrRuO3 monolayer under the illumination, confirmed by cross-section scanning tunneling microscopy (XSTM). Therefore, this study demonstrates a simple route to design and explore the potential low dimensional oxide materials for future optoelectronic devices.
Self-Assembled Ferroelectric Nanoarray
(2019-01-16)
Jiang, Jie
;
Yang, Qiong
;
Zhang, Yi
;
Li, Xiao-Yu
;
Shao, Pao-Wen
Self-assembled heteroepitaxial nanostructures have played an important role for miniaturization of electronic devices, e.g., the ultrahigh density ferroelectric memories, and cause for great concern. Our first principle calculations predict that the materials with low formation energy of the interface (E-f) tend to form matrix structure in self-assembled heteroepitaxial nanostructures, whereas those with high E-f form nanopillars. Under the guidance of the theoretical modeling, perovskite BiFeO3 (BFO) nanopillars are swimmingly grown into CeO2 matrix on single-crystal (001)-SrTiO3 (STO) substrates by pulsed laser deposition, where CeO2 has a lower formation energy of the interface (E-f) than BFO. This work provides a good paradigm for controlling self-ssembled nanostructures as well as the application of self-assembled ferroelectric nanoscale memory.