Search

We investigated the resistive switching behaviors of the metal-copper oxide-metal devices with the enhanced capability in terms of high speed and multi-bit operation. From the analysis of the normal and extended resistive switching behaviors, the voltage-induced resistive changes were modeled and the resistive switching polarity was explained. Also, we proposed and fabricated a dual vacancy-type device structure with an extended resistive switching behavior and demonstrated a high-speed implemental 2-bit multi-bit operation by controlling specifically switch-on voltage pulses. [ABSTRACT FROM AUTHOR]

The mammalian brain is far superior to today's electronic circuits in intelligence and efficiency. Its functions are realized by the network of neurons connected via synapses. Much effort has been extended in finding satisfactory electronic neural networks that act like brains, i.e., especially the electronic version of synapse that is capable of the weight control and is independent of the external data storage. We demonstrate experimentally that a single metal-oxide-metal structure successfully stores the biological synaptic weight variations (synaptic plasticity) without any external storage node or circuit. Our device also demonstrates the reliability of plasticity experimentally with the model considering the time dependence of spikes. All these properties are embodied by the change of resistance level corresponding to the history of injected voltage-pulse signals. Moreover, we prove the capability of second-order learning of the multi-resistive device by applying it to the circuit composed of transistors. We anticipate our demonstration will invigorate the study of electronic neural networks using non-volatile multi-resistive device, which is simpler and superior compared to other storage devices. [ABSTRACT FROM AUTHOR]

We report the demonstration of multilevel operation using Cu/Cu-GeTe/W nonvolatile resistive memory devices for enhanced storage density. We incorporated Cu atoms into GeTe solid-electrolyte switching layers in Cu/Cu-GeTe/W nonvolatile resistive memory devices by applying a bias to the sample holder during a radio-frequency sputtering process. By analyzing the dependence of the device current (resistance) on both the pulse input voltage magnitude and width, we achieved four distinct resistance levels that correspond to the 2-bit operation of a single memory cell. Moreover, a model was suggested and discussed to account for the observed multibit operation. [ABSTRACT FROM PUBLISHER]