We report sub-nanosecond switching of a metal-oxide-metal memristor utilizing a broadband 20 GHz experimental setup developed to observe fast switching dynamics. Set and reset operations were successfully performed in the tantalum oxide memristor using pulses with durations of 105 and 120 ps, respectively. Reproducibility of the sub-nanosecond switching was also confirmed as the device switched over consecutive cycles.

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High‐performance memristors based on AlN films have been demonstrated, which exhibit ultrafast ON/OFF switching times (≈85 ps for microdevices with waveguide) and relatively low switching current (≈15 μA for 50 nm devices). Physical characterizations are carried out to understand the device switching mechanism, and rationalize speed and energy performance. The formation of an Al‐rich conduction channel through the AlN layer is revealed. The motion of positively charged nitrogen vacancies is likely responsible for the observed switching.

Highly reproducible bipolar resistance switching was recently demonstrated in a composite material of Pt nanoparticles dispersed in silicon dioxide. Here, we examine the electrical performance and scalability of this system and demonstrate devices with ultrafast (<100 ps) switching, long state retention (no measurable relaxation after 6 months), and high endurance (>3 × 10(7) cycles). A possible switching mechanism based on ion motion in the film is discussed based on these observations.

A key requirement for using memristors in circuits is a predictive model for device behavior that can be used in simulations and to guide designs. We analyze one of the most promising materials, tantalum oxide, for high density, low power, and high-speed memory. We perform an ensemble of measurements, including time dynamics across nine decades, to deduce the underlying state equations describing the switching in Pt/TaO x /Ta memristors. A predictive, compact model is found in good agreement with the measured data. The resulting model, compatible with SPICE, is then used to understand trends in terms of switching times and energy consumption, which in turn are important for choosing device operating points and handling interactions with other circuit elements.

We measured the real-time switching of metal-oxide memristors with sub-nanosecond resolution and recorded the evolution of the current and voltage during both ON (set) and OFF (reset) events. From these we determined the dynamical behavior of the conductivity for different applied bias amplitudes. Quantitative analysis of the energy cost and switching dynamics showed 115 fJ for ON-switching and 13 pJ for OFF-switching when resistance change was limited to 200%. Results are presented that show a favorable scaling with speed in terms of energy cost and reducing unnecessary damage to the devices.

The design, operation, and characterization of a continuous-wave (CW) tunable second-harmonic 460-GHz gyrotron are reported. The gyrotron is intended to be used as a submillimeter-wave source for 700-MHz nuclear magnetic resonance experiments with sensitivity enhanced by dynamic nuclear polarization. The gyrotron operates in the whispering-gallery mode TE 11,2 and has generated 16 W of output power with a 13-kV 100-mA electron beam. The start oscillation © 2010 IEEE Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Long-term CW operation was evaluated during an uninterrupted period of 48 h, where the gyrotron output power and frequency were kept stable to within ±0.7% and ±6 ppm, respectively, by a computerized control system. Proper operation of an internal quasi-optical mode converter implemented to transform the operating whispering-gallery mode to a Gaussian-like beam was also verified. Based on the images of the gyrotron output beam taken with a pyroelectric camera, the Gaussian-like mode content of the output beam was computed to be 92% with an ellipticity of 12%. NIH Public Access

Abstract-The design and operation of a frequency tunable continuous-wave (CW) 330-GHz gyrotron oscillator operating at the second harmonic of the electron cyclotron frequency are reported. The gyrotron has generated 18 W of power from a 10.1-kV 190-mA electron beam working in a TE -4,3 cylindrical mode, corresponding to an efficiency of 0.9%. The measured start oscillation current over a range of magnetic field values is in good agreement with theoretical start currents obtained from linear theory for successive high order axial modes TE -4,3,q , where q = 1 to 6. Also, the observed frequency range in the start current measurement is in reasonable agreement with the frequency range calculated from numerical simulations. The minimum start oscillation current of the device was measured to be 33 mA. A continuous tuning range of 1.2 GHz was observed experimentally via a combination of magnetic, voltage, and thermal tuning. The gyrotron output power and frequency stabilities were assessed to be ±0.4% and ±3 ppm, respectively, during a 110-hour uninterrupted CW run. Evaluation of the gyrotron microwave output beam pattern using a pyroelectric camera indicated a Gaussian-like mode content of 92% with an ellipticity of 28%. The gyrotron will be used for 500-MHz nuclear magnetic resonance (NMR) experiments with sensitivity enhanced by dynamic nuclear polarization (DNP).Index Terms-Dynamic nuclear polarization (DNP), nuclear magnetic resonance (NMR), second cyclotron harmonic, submillimeter wave, terahertz, tunable gyrotron.