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We describe guanidinium-based organic-inorganic hybrid lead triiodides (GAPbI3) as an active layer in resistive switching structures and compare the switching results to those of the conventional compound, MAPbI3. Both the GAPbI3- and MAPbI3-based ReRAM devices showed bistable switching characteristics with a low operating voltage (<0.25 V) and high on/off ratio (∼106). Remarkably, we found that the GAPbI3-based devices exhibited prolonged switching behaviors for over 40 days under ambient conditions (MAPbI3, only 4 days). The GAPbI3 devices lasted for a larger number of cycles (>1900) in an endurance test and exhibited a longer data storage time (>3 × 104 s) in a retention test. Our results suggest that GAPbI3 has stronger hydrogen bonding in the lattice and thus the potential for application in memory devices. [ABSTRACT FROM AUTHOR]

The authors describe the atomic layer deposition (ALD) of titanium oxysulfide films (TiO2−xSx). A new ALD chemistry of tetrakis(dimethylamido)titanium and hydrogen sulfide is proposed for fabricating amorphous titanium sulfide layers. They found that the resulting films subsequently underwent oxidation upon reactions under the ambient condition, resulting in TiO2−xSx. The resultant structures were analyzed by using x-ray diffraction, transmission electron microscopy, and x-ray photoelectron spectroscopy, indicative of the formation of TiO2−xSx. A combined study of Hall effect measurements and Mott–Schottky analysis showed n-type semiconductor behaviors possessing a good conductivity. Optical properties testify that the present system has a moderate bandgap in between the related binary end compounds such as TiS2 and TiO2. [ABSTRACT FROM AUTHOR]

We report visualization of three-dimensional domain structures in ferroelectric PbTiO3 (PTO) nanotubes (NTs) using piezoresponse force microscopy (PFM). The domain distributions of the x, y, and z-axes in PTO NTs were separately measured out-of and in-planes at angles of 0° and 90° by vertical and lateral PFM. The separately obtained PFM images were combined to reconstruct the complex domain structures based on some basic assumptions and finite element modeling. The cross-sectional domain configurations of the PTO NTs were visualized by the proposed approach. The results can provide insight into complex domain configurations of ferroelectric nanostructures. [ABSTRACT FROM AUTHOR]