Tin oxide artificial synapses for low power temporal information processing.

Lateral memristors configured with inert Pt contacts and mixed phase tin oxide layers have exhibited immediate, forming-free, low-power bidirectional resistance switching. Activity dependent conductance and relaxation in the low resistance state resembled short term potentiation in biological synapses. After scanning probe microscopy, x-ray photoelectron spectroscopy and electrical measurements, the device characteristics were attributed to Joule heating induced decomposition of the minority SnO phase and formation of a SnO2 conducting filament with higher effective n-type doping. Finally, the devices recognized input voltage pulse sequences and spectral data by returning unique conductance states, suggesting suitability for bio-inspired pattern recognition systems.

In situ investigation of thermally influenced phase transformations in (Pb 0.92 Sr 0.08)(Zr 0.65 Ti 0.35)O3 thin films using micro-Raman spectroscopy and X-ray diffraction.

Thin films of ferroelectric strontium-doped lead zirconate titanate [PSZT, (Pb(0.92)Sr(0.08))(Zr(0.65)Ti(0.35))O(3)] deposited by RF magnetron sputtering have been analyzed by in situ analysis techniques. The in situ techniques employed for this study include micro-Raman spectroscopy and X-ray diffraction (XRD), and variations in thin film structure and orientations for temperatures up to 350 degrees C and 750 degrees C for the respective techniques have been studied. The samples analyzed were PSZT thin films deposited on platinum-coated silicon substrates at either room temperature or at 750 degrees C. In situ measurements using micro-Raman spectroscopy and XRD techniques have been used to identify the Curie point for poly-crystalline PSZT thin films and to determine the temperature-activating significant grain growth for room-temperature-deposited PSZT thin films. To study the presence of hysteresis, analysis was carried out during both temperature ramp-up and ramp-down cycles. Raman measurements showed expected bands (albeit weak), and the in situ measurements have detected variations in the crystal structure of the thin film samples, with negligible variations between the heating and cooling cycles. A combination of the Raman and XRD results has shown that the temperature-activating significant grain growth for the room-temperature-deposited films is about 275 degrees C and the Curie point lies between 325 and 400 degrees C. This relatively high Curie point makes these films suitable for wide temperature range applications.