Neuronal dynamics in HfO<sub>x</sub>/AlO<sub>y</sub>-based homeothermic synaptic memristors with low-power and homogeneous resistive switching

2020

Nanomaterials

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In this study, we investigated the synaptic functions of TiN/Ti/TiO2/SiOx/Si resistive random access memory for a neuromorphic computing system that can act as a substitute for the von-Neumann computing architecture. To process the data efficiently, it is necessary to coordinate the information that needs to be processed with short-term memory. In neural networks, short-term memory can play the role of retaining the response on temporary spikes for information filtering. In this study, the proposed complementary metal-oxide-semiconductor (CMOS)-compatible synaptic device mimics the potentiation and depression with varying pulse conditions similar to biological synapses in the nervous system. Short-term memory dynamics are demonstrated through pulse modulation at a set pulse voltage of −3.5 V and pulse width of 10 ms and paired-pulsed facilitation. Moreover, spike-timing-dependent plasticity with the change in synaptic weight is performed by the time difference between the pre- and postsynaptic neurons. The SiOx layer as a tunnel barrier on a Si substrate provides highly nonlinear current-voltage (I–V) characteristics in a low-resistance state, which is suitable for high-density synapse arrays. The results herein presented confirm the viability of implementing a CMOS-compatible neuromorphic chip.

Section: Introductionmentioning

confidence: 99%

Short-Term Memory Dynamics of TiN/Ti/TiO2/SiOx/Si Resistive Random Access Memory

Cho

2020

Nanomaterials

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“…However, unlike a passive nonlinear-resistive two-port emulator circuit, the bi-stability and multi-stability phenomena of Chua Corsage Memristors can be realized by a single device as demonstrated in recent literature [29][30][31]. The NbO 2 Mott memristor [29,30] exhibits an analogous dynamic route to that of 2-lobe CCM which has two stable and one unstable equilibrium points on its dynamic route map (dT/dt vs. T (Figure 1 [29])).…”

Section: Physical Realization Of Ccm Familymentioning

confidence: 99%

“…The universal formulas of switching kinetics (in Section 3) can be applicable to NbO 2 Mott memristor as the PWL dynamic route, and switching kinetics are explicitly similar to 2-lobe CCM. In addition, HfOx/AlOy-based homeothermic memristor [31] has a similar number of stable equilibrium states (i.e., four temperature-dependent equilibrium states corresponding to its four dynamic conductances (Figure 3 in [31])) to that of 6-lobe CCM. When driven by DC input, the homeothermic memristor exhibits four distinct DC V-I curves corresponding to its four temperature-dependent dynamic conductances (Figure 3e and f in [31]) which is identical to 6-lobe CCM (shown in Figures 2c and 10).…”

Section: Physical Realization Of Ccm Familymentioning

confidence: 99%

“…In addition, HfOx/AlOy-based homeothermic memristor [31] has a similar number of stable equilibrium states (i.e., four temperature-dependent equilibrium states corresponding to its four dynamic conductances (Figure 3 in [31])) to that of 6-lobe CCM. When driven by DC input, the homeothermic memristor exhibits four distinct DC V-I curves corresponding to its four temperature-dependent dynamic conductances (Figure 3e and f in [31]) which is identical to 6-lobe CCM (shown in Figures 2c and 10). In spite of the quantitative dissimilarities, the NbO 2 Mott memristor and homeothermic memristor qualitative exhibit the bi-stability and multi-stability phenomena of CC memristors.…”

Section: Physical Realization Of Ccm Familymentioning

confidence: 99%

See 1 more Smart Citation

Nonlinear Dynamics, Switching Kinetics and Physical Realization of the Family of Chua Corsage Memristors

Mannan

2020

Electronics

This article reviews the nonlinear dynamical attributes, switching kinetics, bifurcation analysis, and physical realization of a family of generic memristors, namely, Chua corsage memristors (CCM). CCM family contains three 1-st order generic memristor dubbed as 2-lobe, 4-lobe, and 6-lobe Chua corsage memristors and can be distinguished in accordance with their asymptotic stable states. The 2-lobe CCM has two asymptotically stable equilibrium states and regarded as a binary memory device. In contrast, the versatile 4-lobe CCM and 6-lobe CCM are regarded as a multi-bit-per-cell memory device as they exhibit three and four asymptotic stable states, respectively, on their complex and diversified dynamic routes. Due to the diversified dynamic routes, the CC memristors exhibit a highly nonlinear DC V-I curve. Unlike most published highly-nonlinear DC V-I curves with several disconnected branches, the DC V-I curves of CCMs are contiguous along with a locally active negative slope region. Moreover, the DC V-I curves and parametric representations of the CCMs are explicitly analytical. Switching kinetics of the CCM family can be demonstrated with universal formulas of exponential state trajectories xn(t), time period tfn, and applied minimum pulse amplitude VA and width Δw. These formulas are regarded universal as they can be applied to any piecewise linear dynamic routes for any DC or pulse input and with any number of segments. When local activity, and bifurcation and chaos theorems are employed, CMMs exhibit unique stable limit cycles spawn from a supercritical Hopf bifurcation along with static attractors. In addition, the nonlinear circuit and system theoretic approach is applied to explain the asymptotic stability behavior of CCMs and to design real memristor emulators using off-the-shelf circuit components.

“…Synaptic devices such as RRAM [15][16][17][18][19] and phase change memory (PRAM) [20,21] can reduce the burden of computation compared to a graphics processing unit (GPU)-based deep learning framework by employing weight updating by matrix multiplication. Moreover, a two-terminal RRAM device can 2 of 8 maximize memory density compared to three-terminal devices.…”

Section: Introductionmentioning

confidence: 99%

Enhancing Short-Term Plasticity by Inserting a Thin TiO2 Layer in WOx-Based Resistive Switching Memory

Cho

2020

Coatings

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In this work, we emulate biological synaptic properties such as long-term plasticity (LTP) and short-term plasticity (STP) in an artificial synaptic device with a TiN/TiO2/WOx/Pt structure. The graded WOx layer with oxygen vacancies is confirmed via X-ray photoelectron spectroscopy (XPS) analysis. The control TiN/WOx/Pt device shows filamentary switching with abrupt set and gradual reset processes in DC sweep mode. The TiN/WOx/Pt device is vulnerable to set stuck because of negative set behavior, as verified by both DC sweep and pulse modes. The TiN/WOx/Pt device has good retention and can mimic long-term memory (LTM), including potentiation and depression, given repeated pulses. On the other hand, TiN/TiO2/WOx/Pt devices show non-filamentary type switching that is suitable for fine conductance modulation. Potentiation and depression are demonstrated in the TiN/TiO2 (2 nm)/WOx/Pt device with moderate conductance decay by application of identical repeated pulses. Short-term memory (STM) is demonstrated by varying the interval time of pulse inputs for the TiN/TiO2 (6 nm)/WOx/Pt device with a quick decay in conductance.