Experimental and computational analysis of thermal environment in the operation of HfO2 memristors

Abstract

Neuromorphic computation using nanoscale adaptive oxide devices or memristors is a very promising alternative to the conventional digital computing framework. Oxides of transition metals, such as hafnium (HfOx), have been proven to be excellent candidate materials for these devices, because they show non-volatile memory and analog switching characteristics. This work presents a comprehensive study of the transport phenomena in HfOx based memristors and involves the development of a fully coupled electrothermal and mass transport model that is validated with electrical and thermal metrology experiments. The fundamental transport mechanisms in HfOx devices were analyzed together with the local and temporal variation of voltage, current, and temperature. The effect of thermal conductivity of substrate materials on the filament temperature, voltage ramp rate, and set/reset characteristics was investigated. These analyses provide insight into the switching mechanisms of these oxides and allow for the prediction of the effect of device architecture on switching behavior.

Substrate dependent resistive switching in amorphous-HfOx memristors: an experimental and computational investigation

“…Finally, the validity of experimental results is confirmed by taking two different radii of CFs, namely: 3 nm for SiO 2 /Si and 4 nm for glass substrates, which are more realistic than taking a single size filament as discussed above. Further details of the model are not described in this article for brevity and can be found in the work by Pahinkar et al 35 Fig. 6 shows a comparison of I-V curves from the experiments and the model simulations demonstrating a good agreement, especially on the reset side.…”

“…The basic hypothesis of this thermal modeling is that the RS switching behavior of a filamentary device is controlled by both the applied electric field (E) and local thermal field, generated via joule-heating. For this, a COMSOL physical model that is reported in our recently published article 35 has been used to analyze the intermediate variables such as local temperature and oxygen defect (vacancy) concentration, so that their role in the device performance can be understood. The thermal model considers the drift, diffusion and thermophoresis of oxygen vacancies that are instrumental in creating and suppressing the CF.…”

Mechanism of the Resistivity Switching Induced by the Joule Heating in Crystalline NbO2

“…This energy cost emerges as neighboring orders "bend" away from each other, and as such it is necessary to include in modelling spatially non-uniform systems. [41] Figure 6 plots the results of the MC simulations using the GL free energy given in Equation (10). We observe that the metallic domain of Nb-Nb weakened dimers are clearly formed at a higher voltage but not at the lower voltage, which can be viewed as the direct presentations for "on" and "off" states.…”

“…[1,2] After the discovery of the nanoscale memristor in TiO x , [3] great progress has been made to investigate oxide-based memristors. [4,5] For typical binary oxides, including TiO 2 , TaO 2 , ZrO 2 , HfO 2 , etc., [3,[6][7][8][9][10][11] the resistivity switching is generally attributed to conductive filaments formed by mobile oxygen vacancies. Recently, correlated oxides VO 2 [12,13] and NbO 2 [14][15][16] have come to the spotlight in the study of memristors because their resistivity switching cannot be explained by the filament DOI: 10.1002/qute.202200067 mechanism.…”

Mechanism of the resistivity switching in crystalline NbO$_2$

“…4,5 For typical binary oxides, including TiO 2 , TaO 2 , ZrO 2 , HfO 2 , etc. 3,[6][7][8][9][10][11] the resistivity switching is generally attributed to conductive filaments formed by mobile oxygen vacancies. Recently, correlated oxides VO 2 12,13 and NbO 2 14,15 have come to the spotlight in the study of memristors because their resistivity switching can not be explained by the filament mechanism.…”