Maximum Current Ratio Research Articles

Quantum transport simulations of α-In2Se3 antiferroelectric tunnel junctions

Due to semiconductor characteristics and non-volatile ferroelectricity, two-dimensional (2D) In2Se3 are considered as potential candidates for next-generation storage and computing devices. Based on first principles calculations, we designed antiferroelectric tunnel junctions (AFTJs) using α-In2Se3 as channels. The tunneling barrier height is controlled by the antiferroelectric to ferroelectric (AFE-FE) phase transition of the channel. A maximum current ratio up to 426 is predicted between the AFE and FE phases, enabling the two distinct memory states. By constructing two AFTJs into a calculation unit, the total current can either be fully turned on/off or function as XNOR logic with bias as inputs. Our research provides a new approach to implementing integrated storage and computing devices, making it possible for efficient data-centric applications in the era of big data.

Carrier transport and Negative differential resistance of electrically bipolar devices based on poly(3,4-ethylene-dioxythiophene): Poly (styrene sulfonate) film

A poly (3,4-ethylene-dioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) film sandwiched between copper electrodes was used to create an electrically bipolar device using a conventional casting technique. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray spectroscopy (EDX) were used to investigate the structure, morphological behaviour, and homogeneous distribution of PEDOT conducting grains in the insulator matrix PSS. The device exhibits normal hysteretic electrical behaviour and a negative differential resistance (NDR) effect in the swept current-voltage (I–V) curves. By varying the PEDOT:PSS films' positive charge voltage and charging rate, the NDR effect may be tuned. A maximum current ratio of 103 can exist between the High Conducting State (HCS) and the Low-Conducting State (LCS). Complex impedance measurements of the Cu/PEDOT:PSS/Cu device were carried out at applied ac-voltage amplitude, Vac, range from 0.1 V to 2 V and over the frequency range from 100 Hz to 10 MHz at room temperature. Different models based on ac and dc experimental data are used to characterize and confirmed the carrier transport processes in the HC, LC-States and NDR.

Characteristics assessment of TFT through 2D simulation under different material and structural configurations

This paper presents a performance analysis of indium-gallium-zinc-oxide (IGZO)- and pentacene-based top-gate-top-contact (TGTC) and bottom-gate-top-contact (BGTC) thin film transistors (TFTs). Extensive simulation has been performed to assess the performances in terms of threshold voltage, subthreshold slope, on-off current ratio, mobility, and figure of merit (FoM). Results indicate a trade-off between mobility and current ratio with respect to the permittivity of the dielectric layer, where tantalum oxide (Ta2O[Formula: see text] provides the optimum result in terms of FoM. The mobility of IGZO is significantly higher for both structures, whereas the current ratio for IGZO is higher than pentacene in the BGTC configuration. Comparing the structural configurations, Ta2O5-IGZO-based BGTC achieves [Formula: see text] and [Formula: see text] better mobility and current ratio, respectively, over TGTC structures. The threshold voltage of IGZO-based TFT is observed to increase with the permittivity of the dielectric in TGTC configuration but decrease in BGTC configuration. Meanwhile, the increase in oxide and active layer thicknesses causes a decrease in the threshold voltage. Moreover, both mobility and current ratio improve with a decrease in oxide or active layer thickness. Maximum mobility of 32.30[Formula: see text]cm2/Vs and a maximum current ratio of 7.54E+08 are achieved for Ta2O5-IGZO-based BGTC TFT with 10[Formula: see text][Formula: see text]m channel thickness and 5[Formula: see text][Formula: see text]m oxide thickness.

Coupled NEGF-PSO method for maximizing the current ratio of CNTFETs based on oxide thickness optimization

A method for designing carbon nanotube field-effect transistors (CNTFETs) with optimized oxide thickness is proposed herein. The optimum oxide thickness that provides the maximum current ratio (on/off ratio) is calculated for each design. The effect of oxide thickness on the on/off ratio is investigated by treating it as the independent variable and calculating the on-state and off-state currents. Particle swarm optimization is used to determine the exact optimum oxide thickness to achieve the maximum current ratio, which is one of the most important parameters in switching applications. The optimum insulator thickness is calculated for CNTFETs with different chiral vectors, insulator types, channel lengths and source/drain doping levels. For further study of the CNTFETs, performance parameters including cutoff frequency and transconductance of the devices are also calculated and investigated. The results show that CNTFET designers should select the oxide thickness very carefully, not simply based on reported values in other works. Each design requires its own optimum oxide thickness which provides the maximum on/off current ratio only for that design.

Influence of Dynamic Loading Activation Time on Electro-osmotic Consolidation of Soft Soil

Electro-osmosis is a suitable method for the consolidation of soft soil. However, the significant potential loss caused by the cracking of the soil near the electrode in the later stages of electro-osmosis hinders further improvement of its efficiency. Dynamic loading is applied to overcome this problem. The dynamic loading activation time is considered to strongly influence the performance of the combined electro-osmosis-dynamic loading process. In this paper, the maximum current ratio (MCR) is proposed as an index of the dynamic loading activation time. Laboratory tests were performed with different dynamic loading activation times to confirm the influence of the dynamic loading time on electro-osmosis consolidation. During the combined processes of dynamic loading and electro-osmosis, the current, electric potential, discharged water, and surface settlement were monitored. In the following testing, the water content and undrained shear strength were measured. Compared with the electro-osmosis method alone, electro-osmosis and dynamic loading was found to yield superior performance improvement. The method described in this paper to determine the optimal dynamic loading activation time as a function of the MCR, and electro-osmosis, exhibits potential as an improved approach for the consolidation of soft soil in engineering practice.

Negative differential resistance and carrier transport of electrically bistable devices based on poly(N-vinylcarbazole)-silver sulfide composites

An electrically bistable device has been fabricated based on poly(N-vinylcarbazole) (PVK)-silver sulfide (Ag2S) composite films using a simple spin-coating method. Current–voltage (I-V) characteristics of the as-fabricated devices exhibit a typical electrical bistability and negative differential resistance (NDR) effect. The NDR effect can be tuned by varying the positive charging voltage and the charging time. The maximum current ratio between the high-conducting state (ON state) and low-conducting state (OFF state) can reach up to 104. The carrier transport mechanisms in the OFF and ON states are described by using different models on the basis of the experimental result.

A method for detecting myocardial abnormality by using a current-ratio map calculated from an exercise-induced magnetocardiogram.

A method for making a current-ratio map to determine the ischaemic area of angina pectoris (AP) patients has been developed. This method uses a current-arrow map calculated using a ORS wave from 64-channel magnetocardiogram (MCG) signals. The current-ratio map can be calculated from the ratio of an exercise-induced current vector to an at-rest current vector. The MCG signals of eight patients with angina pectoris (AP) (six patients with effort AP and two patients with variant AP) and four healthy volunteers were measured before and after a two-step exercise test. The current-ratio maps of the six patients with effort AP showed three distinct patterns: a left-circumflex-artery (LCX) pattern; a right-coronary-artery (RCA) pattern; and a left-anterior-descending (LAD) pattern. The maximum current ratios of these three patterns differed from those of normal patterns. The patterns of two patients with variant AP were similar to normal patterns. Furthermore, a comparison of the current-ratio map before and after percutaneous-transluminal-coronary-angioplasty (PTCA) treatment indicated that the cardiac ischaemia was reduced in all patients. An appropriate criterion to diagnose abnormality in a patient with an ischaemic myocardial area seems to be a maximum current ratio exceeding 0.4 to 0.5. Based on these preliminary results, it is believed that the location of an ischaemic area (the coronary artery part) can be estimated by using the ischaemic current-ratio map pattern.

Direct Extraction of Sodium Negative Ions from Sodium Plasma

Diatomic negative ions of Na(Na2-) are extracted with atomic negative ions of Na(Na-) from a low-temperature Na plasma. The extracted currents of these negative ions are experimentally measured as functions of discharge parameters and wall temperatures. The measured extraction characteristics are discussed by comparing the results with those of negative hydrogen and negative lithium ions extracted from the corresponding plasmas. The maximum current ratio of Na2- to Na- for a wall temperature below 235°C is on the order of 0.01, much smaller than that obtained in the sputtering experiment.