NbO2-Mott Memristor: A Circuit- Theoretic Investigation Messaris, Ioannis; Brown, Timothy D.; Demirkol, Ahmet S. ...
IEEE transactions on circuits and systems. I, Regular papers,
12/2021, Letnik:
68, Številka:
12
Journal Article
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This paper presents a circuit-theoretic analysis of a NbO 2 -Mott memristor fabricated at Hewlett-Packard Labs. It investigates mechanisms behind the origin of complexity based on local activity, ...which characterizes the behavior of this outstanding nanodevice. We propose an accurate, particularly simplified version of a recently introduced physical model suitable for large-scale circuit simulations. Following the concept of local activity, we then conduct a small-signal circuit-theoretic derivation of the impedance and associated small-signal equivalent circuit elements to analyze device stability and frequency response. Finally, our analysis reveals locally active operating regions, as well as regions where the device dynamics are positioned on the edge of chaos. The latter regions are crucial for designing bio-inspired computing systems.
In this paper, we analyze the reset transition in bipolar TiN/Ti/HfO2 (10 nm)/Al2O3(2 nm)/W ReRAM devices using a tool that allows studying the temporal behaviour of these devices. This tool, the ...Dynamic Route Map (DRM), provides information about the temporal evolution of the state variable that governs the behaviour of the device, thus allowing an increased insight into resistive switching processes. Here, we show that this DRM is a powerful tool, that may help explaining some non intuitive behaviours of memristors, like the difference in the reset voltage when the inputs are from different frequency or shape. Using this tool, this fact can be explained as a different trajectory on a unique surface defining the device. As a first step, we have used two different models, one based on a physical description, and another one based on the mathematical definition of memristor as a non linear relation between charge and flux. We check that similar DRM can be obtained from both models. Additionally, several series of set-reset transitions have been measured using voltage ramps of different slopes. From the measured transitions, the corresponding resistance has been extracted and, assuming conductive filaments (CF) as the switching mechanism, the corresponding CF radius has been calculated. Using these data, we show that explanations from the model are also supported when using experimental data, thus proving the validity of the approach.
Random telegraph noise (RTN) owns its very name to its assumed stochastic nature. In this paper, we follow up previous works that questioned this stochastic nature, and we investigate this assumption ...using experimentally measured noise coming from properly biased Ni/HfO2 unipolar Resistive RAM memristor nanodevices. We have used established, well–known tools from nonlinear theory to examine the current–noise temporal series. Evaluation results show that this series appears to exhibit not a stochastic, but a deterministic chaotic behavior, also demostrating interesting fractal characteristics in 2D and 3D phase space projections. The presented results clearly advocate for a strong component of complex (chaotic) fluctuation of deterministic origin, instead of a typical (fully stochastic) RTN. This result could pave the path for an enhanced understanding of the mechanisms behind RTN emergence, as well as improve its noise models.
•We have analyzed experimental time series RTN from Ni/HfO2 unipolar Resistive RAM memristor nanodevices.•Established nonlinear dynamics evaluation tools have been utilized in order to characterize•The recorded RTN has been proved to be deterministic chaotic, possessing a fractal structure.•The studied nanodevice dynamics can embedded in a 5-dimensional phase space.
This work introduces a novel Physically Unclonable Function (PUF) based on the characteristics of Light-Emitting Diodes (LEDs) and Light-Detecting Resistors (LDRs) as long as these are combined. ...Specifically, we profit from the variations in the optical output of an LED caused by process variations, as well as from the variations in LDRs. In this way, our work allows for providing a PUF based on optical components, whose electrical response is a function of the used components. Notice that the electrical response refers not only to the static but also to the dynamical behavior. This way, a unique, double-component system can be easily constructed.
We have measured the transition process from the high to low resistivity states, i.e., the reset process of resistive switching based memristors based on Ni/HfO2/Si-n+ structures, and have also ...developed an analytical model for their electrical characteristics. When the characteristic curves are plotted in the current-voltage (I-V) domain a high variability is observed. In spite of that, when the same curves are plotted in the charge-flux domain (Q-phi), they can be described by a simple model containing only three parameters: the charge (Qrst) and the flux (rst) at the reset point, and an exponent, n, relating the charge and the flux before the reset transition. The three parameters can be easily extracted from the Q-phi plots. There is a strong correlation between these three parameters, the origin of which is still under study.
Stochastic logic is a way to emulate analog operations using only digital gates. In this kind of scheme, precision is gained by an increase in the computing time. We have used this framework to ...implement an emulator for a memristor into Matlab using very simple logic operators. Results show excellent agreement between the expected and the obtained results, demonstrating the potential of this approach.
The paper presents a model for I-V characteristics of RRAMs based on Ni/HfO2/Si-n+ structures that can be easily implemented in SPICE. It describes the successive formation and rupture of one or ...several conductive filaments which are responsible for their behavior. For each filament an equivalent circuit is built upon a flux-controlled memristor model whose relationship between the charge and the flux has been particularized to fit the experimental results. The model describes almost perfectly the I-V characteristics during the set and reset operations in quasi-static regime, using a set and a reset fluxes as fitting parameters. However, further work is needed to extend the model to dynamic operation. Experimental work is underway to refine the relationship between the set and reset fluxes and the input rise rate.
Stochastic Logic provides with a methodology that allows the execution of analog operations by means of digital logic. In this work we calculate the expected values and the estimated error for number ...representation in stochastic logic operations. From these two quantities, we calculate the effective number of bits, which represents the effective resolution of the number in stochastic logic operations. Finally, a random number generator (RNG), fundamental block for number representation in stochastic logic and of stochastic logic operations, capable of reducing the representation error is presented and evaluated.
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