Current Pulses to Control the Conductance in RRAM Devices

Due to the high number of reachable conductance levels in resistive switching devices, they are good candidates to implement artificial synaptic devices. In this work, we have studied the control of the intermediate conductance levels in HfO2-based MIM capacitors using current pulses. The set transition can be controlled in a linear way using this kind of signal. The potentiation characteristic is not affected by the pulse length due to the filament formation takes place in very short times. This behavior does not allow using identical pulses to obtain the potentiation characteristic. The transient response of the devices when applying current pulses showed the filament formation is characterized by a peak in the voltage transient signal. No depression characteristic can be obtained using current signals due to the abrupt reset transition. However, the depression characteristic can be obtained using voltage pulses, so combining both signals should allow control the synaptic weight in an appropriate way.