a-SiNx:H-based ultra-low power resistive random access memory with tunable Si dangling bond conduction paths
TL;DR: The introduction of hydrogen in the a-SiNx:H layer provides a new way to control the Si dangling bond conduction paths, and thus opens up a research field for ultra-low power Si-based RRAM.
Abstract: The realization of ultra-low power Si-based resistive switching memory technology will be a milestone in the development of next generation non-volatile memory. Here we show that a high performance and ultra-low power resistive random access memory (RRAM) based on an Al/a-SiNx:H/p(+)-Si structure can be achieved by tuning the Si dangling bond conduction paths. We reveal the intrinsic relationship between the Si dangling bonds and the N/Si ratio x for the a-SiNx:H films, which ensures that the programming current can be reduced to less than 1 μA by increasing the value of x. Theoretically calculated current-voltage (I-V) curves combined with the temperature dependence of the I-V characteristics confirm that, for the low-resistance state (LRS), the Si dangling bond conduction paths obey the trap-assisted tunneling model. In the high-resistance state (HRS), conduction is dominated by either hopping or Poole-Frenkel (P-F) processes. Our introduction of hydrogen in the a-SiNx:H layer provides a new way to control the Si dangling bond conduction paths, and thus opens up a research field for ultra-low power Si-based RRAM.
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TL;DR: A possible way to mimic biological synapse function for energy-efficient neuromorphic systems by using a conventional passive SiNx layer as an active dielectric with complementary metal-oxide-semiconductor compatibility and expandability to three-dimensional crossbar array architecture is provided.
Abstract: In this paper, we present a synapse function using analog resistive-switching behaviors in a SiNx-based memristor with a complementary metal-oxide-semiconductor compatibility and expandability to three-dimensional crossbar array architecture. A progressive conductance change is attainable as a result of the gradual growth and dissolution of the conducting path, and the series resistance of the AlOy layer in the Ni/SiNx/AlOy/TiN memristor device enhances analog switching performance by reducing current overshoot. A continuous and smooth gradual reset switching transition can be observed with a compliance current limit (>100 μA), and is highly suitable for demonstrating synaptic characteristics. Long-term potentiation and long-term depression are obtained by means of identical pulse responses. Moreover, symmetric and linear synaptic behaviors are significantly improved by optimizing pulse response conditions, which is verified by a neural network simulation. Finally, we display the spike-timing-dependent pl...
181 citations
TL;DR: The experimental findings demonstrate that the scaled metal-nitride-silicon memristor device paves the way to realize CMOS-compatible high-density crosspoint array applications.
Abstract: A feasible approach is reported to reduce the switching current and increase the nonlinearity in a complementary metal-oxide-semiconductor (CMOS)-compatible Ti/SiNx /p+ -Si memristor by simply reducing the cell size down to sub-100 nm. Even though the switching voltages gradually increase with decreasing device size, the reset current is reduced because of the reduced current overshoot effect. The scaled devices (sub-100 nm) exhibit gradual reset switching driven by the electric field, whereas that of the large devices (≥1 µm) is driven by Joule heating. For the scaled cell (60 nm), the current levels are tunable by adjusting the reset stop voltage for multilevel cells. It is revealed that the nonlinearity in the low-resistance state is attributed to Fowler-Nordheim tunneling dominating in the high-voltage regime (≥1 V) for the scaled cells. The experimental findings demonstrate that the scaled metal-nitride-silicon memristor device paves the way to realize CMOS-compatible high-density crosspoint array applications.
70 citations
TL;DR: In this paper, the nonlinear resistive switching characteristics of Si3N4-based resistive random access memory (RRAM) devices that contain an Al2O3 tunnel barrier layer to alleviate sneak path currents in the cross-point array structure were extensively investigated.
Abstract: In this letter, we extensively investigate the nonlinear resistive switching characteristics of Si3N4-based resistive random access memory (RRAM) devices that contain an Al2O3 tunnel barrier layer to alleviate sneak path currents in the cross-point array structure. When the compliance current (ICC) exceeds 1 mA, the Ni/Si3N4/TiN device shows both unipolar and bipolar switching with Ohmic characteristics in the low resistance state. Nonlinear resistive switching characteristics were observed for this device when ICC was ≤100 μA. We fabricated Si3N4/Al2O3 bilayer devices with different tunnel barrier layer thickness and characterized their nonlinear characteristics and failure resistance during the reset process. Furthermore, we obtained stable multiple resistance levels in the devices by varying ICC and the stop voltage for the set and reset switching, respectively. Our results suggest that an Al2O3 tunnel barrier layer embedded in Si3N4-based RRAM devices offers considerable potential to realize high-dens...
64 citations
TL;DR: In this article, two resistive memory devices were prepared with different doping concentrations in the silicon bottom electrodes to explore the self-rectifying and nonlinear resistive switching characteristics of Ni/SiNx/p-Si devices.
Abstract: Two resistive memory devices were prepared with different doping concentrations in the silicon bottom electrodes to explore the self-rectifying and nonlinear resistive switching characteristics of Ni/SiNx/p-Si devices. Due to the reduced current overshoot effect, using electroforming at a positive bias can produce bipolar-type resistive switching behavior. A higher self-rectification ratio in the Ni/SiNx/p+-Si device is achieved than in the Ni/SiNx/p++-Si device. The asymmetric I–V characteristics can be explained by the Schottky barrier that suppresses the reverse current, and it is controllable by the size of the conducting path. A conducting path with a high resistance value in a low resistance state is beneficial for a high selection ratio. Moreover, by controlling the compliance current, we demonstrate an improved self-rectifying and selection ratio. The results of our experiment provide a possible way to improve the nonlinear characteristics without the need for a selector device in CMOS compatible cross-point array applications.
47 citations
TL;DR: This study confirmed that integrating a suitable dielectric layer into the conventional RRAM cell is an innovative strategy to simplify the architecture and fabrication process to realize self-rectifying crossbar arrays.
Abstract: A resistive random access memory (RRAM) device with self-rectifying I-V characteristics was fabricated by inserting a silicon nitride (Si3N4) layer between the bottom electrode and solution-processed active material of an iron oxide-graphene oxide (FeOx-GO) hybrid. The fabricated Au/Ni/FeOx-GO/Si3N4/n+-Si memory device exhibited an excellent resistive switching ratio and a rectification ratio higher than 104. In the Au/Ni/FeOx-GO/Si3N4/n+-Si device, resistive switching occurs in both the FeOx-GO and Si3N4 layers separately, resulting in a highly uniform and stable switching performance. The resistive switching from a high resistance state to a low resistance state in the Au/Ni/FeOx-GO/Si3N4/n+-Si device occurs through a trap-assisted tunneling process in the Si3N4 layer, enabled by the FeOx-GO layer which prevents diffusion of the migrating Ni metal into the switching nitride layer. The intrinsic self-rectifying characteristics of our memory devices arise from the asymmetric barriers for electrons tunneling into the traps of the Si3N4 layer which is sandwiched between the top and bottom electrodes having dissimilar work functions. Our study confirmed that integrating a suitable dielectric layer into the conventional RRAM cell is an innovative strategy to simplify the architecture and fabrication process to realize self-rectifying crossbar arrays.
32 citations
References
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TL;DR: A coarse-grained classification into primarily thermal, electrical or ion-migration-induced switching mechanisms into metal-insulator-metal systems, and a brief look into molecular switching systems is taken.
Abstract: Many metal–insulator–metal systems show electrically induced resistive switching effects and have therefore been proposed as the basis for future non-volatile memories. They combine the advantages of Flash and DRAM (dynamic random access memories) while avoiding their drawbacks, and they might be highly scalable. Here we propose a coarse-grained classification into primarily thermal, electrical or ion-migration-induced switching mechanisms. The ion-migration effects are coupled to redox processes which cause the change in resistance. They are subdivided into cation-migration cells, based on the electrochemical growth and dissolution of metallic filaments, and anion-migration cells, typically realized with transition metal oxides as the insulator, in which electronically conducting paths of sub-oxides are formed and removed by local redox processes. From this insight, we take a brief look into molecular switching systems. Finally, we discuss chip architecture and scaling issues.
4,547 citations
"a-SiNx:H-based ultra-low power resi..." refers methods in this paper
...We calculated the I-V curve using equation (2) for comparison with experimental LRS data as shown in Fig....
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4,540 citations
"a-SiNx:H-based ultra-low power resi..." refers background in this paper
...4 eV into equation (1), the potential well qφPF of the trap in P–F effect is determined to be 0....
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...According to equation (1), the value of dynamic dielectric constant εd can be estimated from the slope of ln (J/E) – E plot....
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TL;DR: A comprehensive review of the recent progress in the so-called resistive random access memories (RRAMs) can be found in this article, where a brief introduction is presented to describe the construction and development of RRAMs, their potential for broad applications in the fields of nonvolatile memory, unconventional computing and logic devices, and the focus of research concerning RRAMS over the past decade.
Abstract: This review article attempts to provide a comprehensive review of the recent progress in the so-called resistive random access memories (RRAMs) First, a brief introduction is presented to describe the construction and development of RRAMs, their potential for broad applications in the fields of nonvolatile memory, unconventional computing and logic devices, and the focus of research concerning RRAMs over the past decade Second, both inorganic and organic materials used in RRAMs are summarized, and their respective advantages and shortcomings are discussed Third, the important switching mechanisms are discussed in depth and are classified into ion migration, charge trapping/de-trapping, thermochemical reaction, exclusive mechanisms in inorganics, and exclusive mechanisms in organics Fourth, attention is given to the application of RRAMs for data storage, including their current performance, methods for performance enhancement, sneak-path issue and possible solutions, and demonstrations of 2-D and 3-D crossbar arrays Fifth, prospective applications of RRAMs in unconventional computing, as well as logic devices and multi-functionalization of RRAMs, are comprehensively summarized and thoroughly discussed The present review article ends with a short discussion concerning the challenges and future prospects of the RRAMs
1,129 citations
TL;DR: In this paper, it was shown that at any given temperature and electric field, the current transport is essentially independent of the substrate material, the film thickness, or the polarity of the electrodes.
Abstract: Measurements of current‐voltage characteristics have been performed on Au‐Si3N4‐Mo and Au‐Si3N4‐Si (degenerate substrate) structures of various nitride‐film thicknesses from 300 A to 3000 A and over a range of temperatures. The films are deposited by the process of reaction of SiCl4 with NH3. It is found that at any given temperature and electric field, the current transport is essentially independent of the substrate material, the film thickness, or the polarity of the electrodes.It is proposed that the current‐transport mechanisms are bulk controlled rather than electrode controlled. The conduction‐current density, J, is the sum of three contributions: J = J1+J2+J3, where J1∼E exp {−q[φ1 − (qE/πe0ed)½]/ kT}, J2∼E2 exp (−E2/E), and J3∼E exp (−qφ3/kT). At high fields and high temperatures J1 dominates the current conduction (the Poole‐Frenkel effect or internal Schottky effect); one obtains a barrier height of (1.3±0.2) V for φ1 and a value of 5.5±1 for the dynamic dielectric constant ed. At high fields a...
445 citations
TL;DR: In this paper, the underlying physics behind the success of the thermochemical E model in describing time-dependent dielectric breakdown (TDDB) in SiO2 thin films is presented.
Abstract: The underlying physics behind the success of the thermochemical E model in describing time-dependent dielectric breakdown (TDDB) in SiO2 thin films is presented. Weak bonding states can be broken by thermal means due to the strong dipolar coupling of intrinsic defect states with the local electric field in the dielectric. This dipole-field coupling serves to lower the activation energy required for thermal bond-breakage and accelerates the dielectric degradation process. A temperature-independent field acceleration parameter γ and a field-independent activation energy ΔH can result when different types of disturbed bonding states are mixed during TDDB testing of SiO2 thin films. While γ for each defect type alone has the expected 1/T dependence and ΔH shows a linear decrease with electric field, a nearly temperature-independent γ and a field-independent ΔH can result when two or more types of disturbed bonding states are mixed. The good agreement between long-term TDDB data and the thermochemical model su...
438 citations