Self-assembled PbTiO3 nanoislands of three different shapes with orderly in-plane directions were fabricated on Pt∕SrTiO3 substrates by metalorganic chemical vapor deposition. The shapes of the nanoislands were triangular-shaped (width 50–110nm, height 20–30nm), triangular-prism-shaped (width 50–110nm, length 100–550nm, height 10–30nm) and square-shaped (width 40–130nm, height 4–10nm) on Pt∕SrTiO3(111), (101), and (001), respectively. The PbTiO3 nanoislands were epitaxially grown on the Pt∕SrTiO3 substrates and consisted of {100} and {001} facets irrespective of the orientation of the substrates indicating that structural control of shape and in-plane direction of self-assembled PbTiO3 nanoislands can be achieved through epitaxial relations. The self-assembled PbTiO3 nanoislands with three different shapes were found to be ferroelectric by piezoresponse force microscopy.
We report on the synthesis of PbTiO 3 -and Pb(Zr,Ti)O 3 (PZT)-covered ZnO nanorods by metalorganic chemical vapor deposition (MOCVD) and their piezoelectric properties. Single-crystal ZnO nanorods with diameters of 140 -230 nm and lengths of 13 m were grown on SiO 2 / Si by a self-assembly process using MOCVD. Subsequently, polycrystalline PbTiO 3 and PZT were also deposited on the ZnO nanorods by MOCVD. Scanning and transmission electron microscopy revealed that PbTiO 3 and PZT uniformly covered the ZnO nanorods with aspect ratios above 50. Piezoelectric force microscopy revealed that PbTiO 3 -and PZT-covered ZnO nanorods showed a piezoresponse of 50 -100 pm/V. #
Thin oxides grown on silicon substrate in which Cu+ ions had been implanted before oxidation were studied by transmission electron microscope (TEM) and scanning TEM imaging methods. Cu precipitates, stacking faults, and dislocations appeared at the SiO2/Si interface on the degraded specimens. The Cu precipitates reduce the breakdown strength by local thinning of the oxide thickness. Stacking faults and dislocations, however, do not reduce the breakdown strength.
By applying scanning nonlinear dielectric microscopy (SNDM), we succeeded in clarifying that electrons existed in the poly-Si layer of the floating gate of a flash memory. The charge accumulated in the floating gate can be detected by SNDM as a change in the capacitance of the poly-Si (floating gate) by scanning the surface of the SiO(2)-SiN(4)-SiO(2) (ONO) film covering the floating gate. There was a clear black contrast region in the SNDM image of the floating gate area, where electrons were injected. However, no clear contrast appeared in the floating gate where electrons were not injected. We confirmed that SNDM is one of the most useful methods of observing the charge accumulated in flash memory.
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