Published online by Cambridge University Press: 12 January 2016
In this work we explore the mechanisms responsible for Random Telegraph Noise(RTN) fluctuations in HfOx Resistive Random Access Memory (RRAM)devices. The statistical properties of the RTN are analyzed in many operatingconditions exploiting the Factorial Hidden Markov Model (FHMM) to decompose themultilevel RTN traces in a superposition of two-level fluctuations. This allowsthe simultaneous characterization of individual defects contributing to the RTN.Results, together with multi-scale physics-based simulations, allows thoroughlyinvestigating the physical mechanisms which could be responsible for the RTNcurrent fluctuations in the two resistive states of these devices, includingalso the charge transport features in a comprehensive framework. We consider twopossible options, which are the Coulomb blockade effect and the possibleexistence of metastable states for the defects assisting charge transport.Results indicate that both options may be responsible for RTN currentfluctuations in HRS, while RTN in LRS is attributed to the temporary screeningeffect of the charge trapped at defect sites around the conductive filament.