Resistance Change Behavior Research Articles

Humidity sensitive memristor based on Ni–Al layered double hydroxides

Reaping the advantages of their exceptional humidity-sensitive elements, humidity sensors exhibit a remarkable ability to adapt to alterations in ambient moisture levels. The significance of the humidity sensor in biological detection is progressively growing, owing to this characteristic. This work examines the impact of humidity on the resistive switching properties Ni–Al layered double hydroxides (LDHs) memristor. As the porous Ni–Al LDHs material contains a significant number of hydroxyl groups, the Ni–Al LDHs memristor exhibits remarkable sensitivity to changes in humidity. As the relative humidity level increases, a conspicuous decrease is observed in resistance of low resistance state, which attributed to the transition of protons facilitated by water. The humidity detection range of the Ni–Al LDHs memristor is from 30 RH% to 95 RH%, and it exhibits a sensitivity of 101.72 mV/RH. The Ni–Al LDHs memristor exhibits humidity sensitive resistive switching characteristics. In different humidity environments can produce a dynamic change between high and low resistance state switching. An artificial humidity sensing system by utilizing the unique resistance change behavior in Ni–Al LDHs memristor induced by humidity was demonstrated.

Halide Perovskites-Based Diffusive Memristors for Artificial Mechano-Nociceptive System.

Numerous efforts for emulating organ systems comprised of multiple functional units have driven substantial advancements in bio-realistic electronics and systems. The resistance change behavior observed in diffusive memristors shares similarities with the potential change in biological neurons. Here, the diffusive threshold switching phenomenon in Ag-incorporated organometallic halide perovskites is utilized to demonstrate the functions of afferent neurons. Halide perovskites-based diffusive memristors show a low threshold voltage of ≈0.2V with little variation, attributed to the facile migration of Ag ions uniformly dispersed within the halide matrix. Based on the reversible and reliable volatile threshold switching, the memristors successfully demonstrate fundamental nociceptive functions including threshold firing, relaxation, and sensitization. Furthermore, to replicate the biological mechano-nociceptive phenomenon at a system level, an artificial mechano-nociceptive system is built by integrating a diffusive memristor with a force-sensing resistor. The presented system is capable of detecting and discerning the detrimental impact caused by a heavy steel ball, effectively exhibiting the corresponding sensitization response. By further extending the single nociceptive system into a 5 × 5 array, successful stereoscopic nociception of uneven impulses is achieved in the artificial skin system through array-scale sensitization. These results represent significant progress in the field of bio-inspired electronics and systems.

Resistance Ratio Enhancement in Phase-Change RF Switches at Cryogenic Temperatures

This letter reports the dc and radio frequency (RF) performance of the phase-change RF switches (PCRS) as a function of temperature. Resistance change behavior of the germanium telluride (GeTe) material is experimentally investigated over 77 to 335 K. The device shows metallic behavior in the crystalline state which exhibits consistent low resistivity over a wide temperature range, while in the amorphous state, resistance increases to more than eleven orders of magnitude as a function of decreasing temperature from 300 to 77 K. Device current–voltage (IV) characteristics and the RF performance are investigated for multiple device cycles. The RF performance of the PCRS is reported with and without microheater are examined to confirm the performance variation of the phase-change switches at cryogenic temperatures.

Atomic drift-less electromigration model for submicron copper interconnects

Electromigration in chip level interconnect is commonly described by atomic drift due to electron-wind force that arises from electron-ion momentum transfer. As an alternative to this model, in early 1980’s, Sah proposed a two dimensional analytical ‘void-surface bond-breaking’ model by dropping the atomic drift term that resulted from electron-wind force (in his book ‘Fundamentals of Solid-State Electronics’) and the rate of change of area of void is computed. Due to the continuous down scaling and evolution of interconnect patterning technologies, the void growth process in modern interconnect becomes more complex and electromigration failures are found to be catastrophic in nature instead of gradual type failures observed in early days. In this work, Sah’s model is revisited from the perspective of its applicability to modern submicron copper interconnects. The electromigration-induced resistance change behavior is analytically derived considering a three-dimensional atomic drift-less model. A good correlation between the findings of our model with experimental observations is presented. Keywords: Analytical model, Copper, Drift-less, Electromigration, Resistance change, Time to failure

Resistance Change Behavior Under Voltage Pulses at Reset Process of Ti/HfO2/Au-Reram with Various HfO2 Layer Conditions

1. Introduction Recently the application of ReRAM to artificial synapse has been paid much attention in the field of neuromorphic computing([1],[2]). For the implementation of neuromorphic synaptic devices, gradual resistance change response by applying voltage pulse trains is required. We investigated the condition of Ti/HfOx/Au-ReRAM to possess gradual resistance change by changing sputtering conditions of HfOx layer. 2. Sample preparation and experiments Figure 1 shows the structure of Ti/HfOx/Au device. For deposition of HfOx film, we used reactive sputtering with Ar and O2 mixture gases. At this time, we adopted two types of Ar/O2 flow ratios, which is (1)7.8 : 15.6 sccm and (2)7.8 : 2.0 sccm. These devices have a bipolar memory characteristic. SET occurs when a positive voltage is applied, and RESET occurs when a negative voltage is applied. We measured resistance change of RESET process of the ReRAM device with applying DC voltage pulses. 3. Results and discussion Figure 2 shows resistance change behavior with applying voltage pulses at RESET process. Pulse width is 1.0 uA and pulse period is 2.0 uA. Figure 2(a) is the resistance change behavior of device (1) with constant amplitude voltage pulses. Resistance change was rarely observed when pulse amplitude is -1.5 V, however, gradual resistance change more than 1 digit was observed when pulse amplitude is -1.6 V. Moreover, when we applied -1.7 V, gradual resistance change more than 2 digits within 40 pulses was observed. In the case of this device, resistance change was ideal for the use of neuromorphic synaptic device. Figure 2(b) is the results of device (2). Gradual resistance change was observed after 60 pulses when pulse width is -1.5 V. However resistance increased more than 3 digits after a few pulses were applied when pulse amplitudes were -1.6 V and -1.7 V. In the case of device (2), resistance change is almost binary and it is not suitable for use of artificial synapse device. The difference of resistance change behavior may come from spatial variation of oxygen vacancies. For further understanding of the mechanisms, we will evaluate the difference of atomic composition of HfOx layer by XPS and XRD.

Chronological change of electrical resistance in GeCu2Te3 amorphous film induced by surface oxidation

Unusual chronological electrical resistance change behavior was investigated for amorphous GeCu2Te3 phase change material. More than a 1 order decrease of electrical resistance was observed in the air even at room temperature. The resistance of the amorphous film gradually increased with increasing temperature and then showed a drop upon crystallization. Such unusual behavior was attributed to the oxidation of the amorphous GeCu2Te3 film. From the compositional depth profile measurement, the GeCu2Te3 film without any capping layer was oxidized in air at room temperature and the formed oxide was mainly composed of germanium oxide. Consequently, a highly-conductive Cu-rich layer was formed in the vicinity of the surface of the film, which reduced the total resistance of the film. The present results could provide insight into the chronological change of electrical resistance in amorphous chalcogenide materials, indicating that not only relaxation of the amorphous, but also a large atomic diffusion contributes to the chronological resistance change.

SABiT 공법적용 인쇄회로기판의 은 페이스트 범프 크기 및 제작 조건에 따른 전기 저항 특성

We investigated the resistance change behavior of SABiT (Samsung Advanced Bump interconnection Technology) technology-applied PCB (Printed Circuit Board) with the various bump sizes and fabrication conditions. Many testing samples with different bump size, prepreg thickness, number of print on the formation of Ag paste bump, were made. The resistance of Ag paste bump itself was calculated from the Ag paste resistivity and bump size, measured by using 4-point probe method and FE-SEM (Field Emission Scanning Electron Microscope), respectively. The contact resistance between Ag paste bump and conducting Cu line were obtained by subtracting the Cu line and bump resistances from the measured total resistance. It was found that the contact resistance drastically changed with the variation of Ag paste bump size and the contact resistance had the largest influence on total resistance. We found that the bump size and contact resistance obeyed the power law relationship. The resistance of a circuit in PCB can be estimated from this kind of relationship as the bump size and fabrication technique vary.

Abnormal bipolar-like resistance change behavior induced by symmetric electroforming inPt/TiO2/Pt resistive switching cells

Abnormal bipolar-like resistive changes are reported inTiO2 thin films sandwiched between Pt top and bottom electrodes. The abnormal behavior isshown relying on the applied voltage range. That is, normal bipolar switching is also shownin the same sample with the optimized voltage range. In the abnormal mode, both set- andreset-like changes in resistance take place under the same polarity of the applied voltage.This abnormal behavior is considered to be due to symmetric electroforming which isassumed to activate electrochemical reactions involving oxygen vacancies at bothPt/TiO2 interfaces. We analyze the abnormal behavior in terms of the interfacial resistive switchingtaking place on both interfaces nearly simultaneously.