Low Power Consumption Devices Research Articles

Unlocking amplified magneto-photocurrent using multi-field manipulation in nonfullerene organic bulk heterojunction systems.

An effective manipulation of polaron pairs (PPs) for realizing amplified magneto-photocurrent (AMPC) is of critical importance toward the development of low power consumption and high-performance organic spin-optoelectronic devices, for instance magneto-photo-volatile memories. By far, it is challenging and there is a lack of method to reach AMPC. The typical magneto-photocurrent due to the light-matter interanion is primarily for unveiling the spin-dependent electron-hole dissociation in organic solar cells. Herein, we achieved an AMPC of ∼140% in nonfullerene organic bulk heterojunction systems at room temperature. We found that the amplification can be effectively triggered by a multi-field to a large number of photogenerated PPs at intermediate charge transfer states. We further postulate that, at steady state, they may experience a cyclic photophysical process due to the triplet-exciton polaron interaction. This study paves the way for the realization of AMPC in the organic spin-optoelectronic system.

Bias voltage modulated electric transport properties in Fe65Co35/Hf0.5Zr0.5O2 films

We demonstrate the bias voltage modulated electric transport properties in Fe65Co35 (FeCo) films deposited on Hf0.5Zr0.5O2 (HZO) films. Intrinsic multiferroicity have been characterized for the FeCo/HZO heterostructures by analyzing the ferroelectric polarizations and imaging the magnetic domains. We show that, upon the application of bias voltages on the FeCo/HZO heterostructures, the current-voltage (I-V) curves of FeCo films can be regulated, giving rise to different resistance states, enabled partly by strain-mediated magnetoelectric coupling effect. The strain coupling effect between HZO and FeCo films is elucidated by simulating the volumetric strain of the FeCo/HZO films under the action of applied voltages. Through additional analysis, the bias voltage modulated electric transport properties could also be linked with charge-mediated magnetoelectric coupling effect. We anticipate that our work will inspire further studies on low-power consumption and high-density electronic devices.

Ultrafast manipulations of nanoscale skyrmioniums

The advancement of next-generation magnetic devices depends on fast manipulating magnetic microstructures at the nanoscale. A universal method is presented for rapid and reliable generating, controlling, and driving nano-scale skyrmioniums, through high-throughput micromagnetic simulations. Ultrafast switches are realized between skyrmionium and skyrmion states and rapidly change their polarities in monolayer magnetic nanodisks by perpendicular magnetic fields. The transition mechanism by alternating magnetic fields differs from that under steady magnetic fields. New skyrmionic textures, such as flower-like and windmill-like skyrmions, are discovered. Moreover, this nanoscale skyrmionium can move rapidly and stably in nanoribbons using weaker spin-polarized currents. Explicit discussions are held regarding the physical mechanisms involved in ultrafast manipulations of skyrmioniums. This work provides further physical insights into the manipulation and application of topological skyrmionic structures for developing low-power consumption and nanostorage devices.

Reconfigurable Resistive Switching in VO2/La0.7Sr0.3MnO3/Al2O3 (0001) Memristive Devices for Neuromorphic Computing.

The coexistence of nonvolatile and volatile switching modes in a single memristive device provides flexibility to emulate both neuronal and synaptic functions in the brain. Furthermore, such a device structure may eliminate the need for additional circuit elements such as transistor-based selectors, enabling low-power consumption and high-density device integration in fully memristive spiking neural networks. In this work, we report dual resistive switching (RS) modes in VO2/La0.7Sr0.3MnO3 (LSMO) bilayer memristive devices. Specifically, the nonvolatile RS is driven by the movement of oxygen vacancies (Vo) at the VO2/LSMO interface and requires a higher biasing voltage, whereas the volatile RS is controlled by the metal-insulator transition (MIT) of VO2 under a lower biasing voltage. The simple device structure is electrically driven between the two RS modes and thus can operate as a one selector-one resistor (1S1R) cell, which is a desirable feature in memristive crossbar arrays to avoid the sneak-path current issue. The RS modes are found to be stable and repeatable and can be reconfigured by exploiting the interfacial and phase transition properties, and thus, they hold great promise for applications in memristive neural networks and neuromorphic computing.

Dynamics of a piezoelectric vibration energy harvester with a pseudoelastic SMA spring

The development of small-scale and low power consumption devices has been motivating the design of intelligent mechanisms, exhibiting a wide power density spectrum across various external sources. Smart materials come up as an attractive alternative due to their intrinsic multi-coupling between different physical domains. In this context, piezoelectric materials allow conversion of mechanical energy of movement into electrical power through the direct piezoelectric effect. This work investigates a piezoelectric energy harvester combined with a shape memory alloy (SMA) spring to explore the combination of both the smart materials for energy harvesting. The pseudoelastic hysteretic effect of SMA is explored in order to passively change the internal system properties such as stiffness and damping during the harvesting process. Numerical analyses are performed considering the normalized power converted by the harvester, focusing on the influence of the SMA martensite phase transformation under different scenarios. The results exhibit an increment in the harvester bandwidth when compared with a traditional linear piezoelectric energy harvester.

Area-selective atomic layer deposition on 2D monolayer lateral superlattices

The advanced patterning process is the basis of integration technology to realize the development of next-generation high-speed, low-power consumption devices. Recently, area-selective atomic layer deposition (AS-ALD), which allows the direct deposition of target materials on the desired area using a deposition barrier, has emerged as an alternative patterning process. However, the AS-ALD process remains challenging to use for the improvement of patterning resolution and selectivity. In this study, we report a superlattice-based AS-ALD (SAS-ALD) process using a two-dimensional (2D) MoS2-MoSe2 lateral superlattice as a pre-defining template. We achieved a minimum half pitch size of a sub-10 nm scale for the resulting AS-ALD on the 2D superlattice template by controlling the duration time of chemical vapor deposition (CVD) precursors. SAS-ALD introduces a mechanism that enables selectivity through the adsorption and diffusion processes of ALD precursors, distinctly different from conventional AS-ALD method. This technique facilitates selective deposition even on small pattern sizes and is compatible with the use of highly reactive precursors like trimethyl aluminum. Moreover, it allows for the selective deposition of a variety of materials, including Al2O3, HfO2, Ru, Te, and Sb2Se3.

Parallel-pipelined-memory Blowfish FPGA-based radio system with improved power-throughput for secured IoT network

The Internet of Things (IoT) has emerged as a disruptive force, transforming industries, cities, and daily life in a time of unprecedented connection. This outcome has called for robust security, reliability, and efficient power management for the IoT network. The security of small mobile devices within the IoT network has become a pressing concern due to the multitude of wireless vulnerabilities that threaten data transmission, the harsh wireless environment for data transmission, and the need for low-power consumption devices. This study proposed the development of a new parallel-pipelined-memory (P2M) Blowfish field programmable gate array (FPGA)-based radio system as a prototype of a secured mobile device for IoT application. The FPGA platform verified the proposed system, indicating a minimum of 64 % power-throughput improvement. In this case, the hardware utilisation was reduced by 3.5 % compared to the recently published works. Meanwhile, the real-time transmission analysis of the suggested P2M Blowfish radio system in a non-line-of-sight (NLOS) indoor environment indicated that the transmitted data over 2.4 GHz ZigBee standard at 10 dBm radio frequency (RF) power level demonstrated the optimum signal quality with received signal strength and signal-to-noise ratio (SNR) of −34.58 dBm and 39.06 dB, respectively. This feature also included a 6.25 × 10−3 minimum bit error rate (BER) at 61 m as the maximum communication range. Thus, the P2M Blowfish FPGA-based radio system could improve the security, reliability, and power efficiency of IoT networks.

Ultralow Voltage Resistive Switching in Hafnium–Zirconium Oxide

AbstractUltralow SET and RESET voltage are essential for high‐density, low‐power, and small heat dissipation nonvolatile random‐access memory (NVRAM) elements. A nanoscale polycrystalline Hf0.75Zr0.25O2 (HZO) thin films on Pt/Si substrate are fabricated and investigated for suitability for bipolar resistive switching. The device illustrates monoclinic and tetragonal/orthorhombic phases with weak ferroelectricity and robust resistive switching. Small remanent polarization (≈0.1 μC cm−2) may assist in the height reduction of barrier height and ease the electron for transport. Remarkably, the Al/HZO/Pt/Si device, consisting of thin films with 10 and 5 nm thicknesses, exhibits a switching voltage below −30 mV from a low‐resistance state (LRS) to a high‐resistance state (HRS). It shows a significant ROFF/RON ratio of 106, making it suitable for low power consumption and minimal heat dissipation devices. Moreover, the utilization of an ultrathin film (5 nm) results in an improved reduction (< 0.7 V) of the operating window at the positive voltage. Direct tunneling and the Fowler–Nordheim tunneling model are performed in current–voltage (I–V) data to study the charge transportation behavior over a trapezoidal and triangular potential barrier. These results of the HZO candidate may stimulate the futuristic nonvolatile resistive random‐access memory (ReRAM) in the optoelectronic industry.

Magnetoelectric behaviour of Pb-free Na0.5Bi0.5TiO3-Ni0.5Co0.5Fe2O4 particulate novel ceramic composites

Magnetoelectric (ME) multiferroic composites are more promising candidates for low-power consumption devices, next-generation spintronic devices, and multistate memory devices since they exhibit significantly higher Magnetoelectric interaction over single-phase multiferroics. In this regard magnetic behaviour, dielectric, and magnetoelectric characteristics of a novel Pb-free (1-x) Na0.5Bi0.5TiO3-(x) Ni0.5Co0.5Fe2O4, (x = 0, 0.2, 0.4, 0.6, 0.8 & 1) particulate composites were explored. Solid-state synthesis was adopted to prepare the single-phase Na0.5Bi0.5TiO3 (NBT), Ni0.5Co0.5Fe2O4 (NCFO), and their composites. The presence of rhombohedral NBT and cubic inverse spinel NCFO in the composites were confirmed with X-ray diffraction (XRD) patterns. Microstrain (ε) induced in the prepared samples was estimated by using the Williamson-Hall (W-H) method. The piezoelectric NBT phase shows the tensile strain and the ferromagnetic NCFO shows the comprehensive strain. Among all the composites 0.8NBT-0.2NCFO shows a higher strain value of 0.012%, and the decrement in the strain values was observed upon increases in ferrite concentration. Backscattered scanning electron microscope (BS-SEM) images revealed the existence of highly dense uniformly distributed elements and Energy dispersive spectroscopy (EDS) confirmed the existing elements in the composites. UV–vis absorbance spectra disclosed a rise in energy gap values from 1.14 eV to 3.0 eV with increasing NBT percentage. Variations of dielectric permittivity and dielectric loss with respect to AC frequency were studied at room temperature (RT), and the 0.2NBT-0.8NCFO sample shows a high dielectric permittivity of 8500 at ∼100Hz. M − H (Magnetization-Magnetic field) hysteresis loops demonstrate the pure ferrite phase has a coercive field (Hc) = 578 Oe, remnant magnetization (Mr) = 21.43 emu/g and saturation magnetization (Ms) = 71.29 emu/g. The Ms and Mr values in the composites are enhanced with increasing ferrite percentage. Studies on ME behaviour of (1-x) NBT-(x) NCFO, (x = 0.2,0.4,0.6 & 0.8) show the coupling effect between both the phases at room temperature and the highest coupling coefficient value 3.16mV/Cm. Oe was observed for the 0.8NBT-0.2NCFO further the reasons and mechanisms are discussed.

Effect of interface quality on spin Hall magnetoresistance in Pt/MgFe2O4 bilayers

We report on spin Hall magnetoresistance (SMR) in bilayers composed of Pt and magnetic insulator MgFe2O4 (MFO) with spinel structure. The Pt thickness dependence of the SMR reveals that annealing of the MFO surface before depositing the Pt layer is crucial for a large SMR with better interface quality. We also found that oxygen pressure during the MFO growth hardly affects the SMR, while it influences the magnetic property of the MFO film. Our findings provide important clues to further understanding the spin transport at interfaces containing magnetic insulators, facilitating development of low power consumption devices.

High-performance self-powered solar-blind ultraviolet photodetector based on a 4H-SiC/ZnGa2O4 heterojunction and its application in optical communication

With the urgent demand for low power consumption, environment-friendly, and portable devices, self-powered solar-blind ultraviolet (UV) photodetectors that only rely on built-in electric fields without external power sources have received extensive attention. In this paper, we have demonstrated a self-powered solar-blind UV photodetector based on a 4H-SiC/ZnGa2O4 heterojunction, along with its application in optical communication. At 0 V bias, the device exhibits a peak responsivity of 115 mA/W with an external quantum efficiency of 58.4% at 244 nm, a fast response speed with a rise/decay time of 18.36/16.15 ms, and a high UV-vis rejection ratio of 4.5 × 104, suggesting that the device has an excellent self-powered solar-blind UV photodetection performance. The exceptional performance of the photodetector is mainly attributed to the 4H-SiC/ZnGa2O4 type I heterojunction with a large conduction band offset (ΔEC = 0.99 eV) and a large valence band offset (ΔEV = 0.75 eV), which is determined by the x-ray photoelectron spectroscopy technique. Moreover, the solar-blind UV optical communication is realized by utilizing the 4H-SiC/ZnGa2O4 heterojunction device to receive signals modulated by the solar-blind UV light. This work provides an effective approach to realizing high-performance self-powered solar-blind UV photodetectors and their potential applications in optical communication.

Energy harvesting in self-sustainable IoT devices and applications based on cross-layer architecture design: A survey

The Internet of Things (IoT) is envisioned to become a driving force in the evolution of fifth-generation (5G) mobile networks, autonomous continuous monitoring and control platforms, and low-power consumption devices. Conventionally, these devices are battery-operated. The battery lifespan degrades faster in the case of continuous monitoring devices. Limited battery lifetime motivates us to investigate an eco-friendly solution to solve the issue of limited battery life and frequent replacement. Energy harvesting (EH) is a key-enabling technique that provides a viable solution to the challenge at hand. EH minimizes battery dependence by collecting energy from ambient sources. Although several studies have been conducted on EH-IoT networks, a tutorial on a possible mapping between the use cases/application to the IoT devices and the IoT devices to EH power source still needs to be included. To address this gap, we classify IoT devices based on their applications. Based on the different interfacing sections of layer architecture design of IoT device, this paper tries to fill the gap between IoT applications and the self-sustainable IoT system design. Next, each interfacing section is categorized into layer architecture of IoT device to study layer-specific power requirements (or demand) versus EH sources (or supply). We have considered various applications like agriculture, healthcare, industry, city, security, transportation, and water management. Further, we discuss different energy sources to harness ambient energy and the method to store the harvested energy. Then, the widely used standards and the various steps taken for the interoperability and compatibility of EH-IoT are outlined to understand the elements of the EH interface. Finally, we point out future research issues requiring specific attention for deploying self-sustainable IoT-based delay-limited applications.

Surface topography detection based on an optical differential metasurface.

Surface topography detection can extract critical characteristics from objects, playing an important role in target identification and precision measurement. Here, an optical method with the advantages of low power consumption, high speed, and simple devices is proposed to realize the surface topography detection of low-contrast phase objects. By constructing reflected light paths, a metasurface can perform spatial differential operation via receiving the light directly reflected from a target. Therefore, our scheme is experimentally demonstrated as having remarkable universality, which can be used not only for opaque objects, but also for transparent pure phase objects. It provides a new, to the best of our knowledge, application for optical differential metasurfaces in precise detection of microscale surface topography.

A QCA placement and routing algorithm based on the SA algorithm

ABSTRACT In the Beyond Moore era, QCA (Quantum-dot Cellular Automata) has been widely studied because of its low power consumption and high device concentration. As the core of chip design, EDA technology has become an indispensable step in QCA research. It refers to the use of computer-aided design software to complete large-scale circuit function design, logic synthesis, placement and routing, design rule check and other processes. In the present study, there are still many defects in QCA placement and routing. The main problems it faces are low success rate, too large area and too many cross lines. To address these problems, our team had proposed a hybrid strategy based on the genetic algorithm and the improved A-star algorithm. But the running time of the previously proposed algorithm is not satisfying, besides it lacks self-adaption feature which is important as the problem size varies among different circuits. This paper replaces the genetic algorithm with a simulated annealing algorithm, and introduces a self-adaption strategy to better accommodate different circuit sizes. Experimental results show that the new algorithm combination possesses a higher success rate, lower running time and more intelligent adaption ability.

Large‐Scale N‐Type FET and Homogeneous CMOS Inverter Array Based on Few‐Layer MoTe2

Abstract2D MoTe2 is regarded as a favorable candidate for semiconductor nanoelectronics integration. Chemical‐vapor‐deposition‐grown MoTe2 usually presents p‐type characteristics. In order to realize basic electronic units like complementary metal‐oxide‐semiconductor (CMOS) inverter, controllable fabrication of p‐ and n‐type transistors at large scale is of vital importance. Here, large‐scale MoTe2 n‐channel field‐effect transistor (n‐FET) arrays are successfully fabricated with seamless coplanar metallic 1T′‐WTe2 contacts to reduce contact resistance. High‐k HfO2 serves as a gate dielectric and its atomic‐layer‐deposition (ALD) process causes an n‐doping effect on the 2H‐MoTe2 channel. The FETs perform typical n‐type characteristics with average electron density and on/off ratio of ≈1.7 × 1013 cm−2 and 2.1 × 104, respectively. Furthermore, large‐scale homogeneous CMOS inverter arrays are fabricated, showing clear logic swing with low power consumption (≈0.4 nW) and high device yield (≈92%). Notably, their voltage transfer characteristics exhibit small hysteresis, and they work well after being kept in air for 16 months, indicating high device stability. The statistical results show that both the n‐FETs and CMOS inverters have high uniformity and reliability in performance. Significantly, this fabrication method is free from transfer processes and compatible with traditional silicon technology. This work paves the way for the application of few‐layer MoTe2 in semiconductor nanoelectronics integration.

All-Solution-Driven Thin-Film Transistor With Low Power Dissipation for Logic Electronics and Neuronal Synapse

For the realization of low-power consumption brain-inspired neuromorphic devices which mimic the biological neuronal information processing methodology, the development of transistors capable of synaptic behaviors and neuronal computation has attracted widespread attention. However, ultrathin, solid-state neuromorphic devices with ultralow energy consumption are still in the exploration stage. Herein, based on an all-solution strategy, oxide-based electrical-double-layer (EDL) thin film transistors (TFTs) have been constructed, demonstrating good operational stability and excellent logic operation functions. Motivated by these excellent characteristics, the TFTs devices triggered by electrical pulses can mimic synaptic behaviors, including excitatory postsynaptic current (EPSC) and paired-pulse facilitation (PPF). In addition, response to electrical stimulus, high-pass filtering characteristics, and short-term memory (STM) and long-term memory (LTM) characteristics have been achieved and investigated. These results reported here have demonstrated that all-solution-driven high-performance oxide-based TFTs enable the achievement of logic electronics with low-power consumption and brain-inspired neuromorphic devices.

Strong interlayer coupling in p-Te/n-CdSe van der Waals heterojunction for self-powered photodetectors with fast speed and high responsivity.

Self-driven photodetectors, which can detect optical signals without external voltage bias, are highly attractive in the field of low-power wearable electronics and internet of things. However, currently reported self-driven photodetectors based on van der Waals heterojunctions (vdWHs) are generally limited by low responsivity due to poor light absorption and insufficient photogain. Here, we report p-Te/n-CdSe vdWHs utilizing non-layered CdSe nanobelts as efficient light absorption layer and high mobility Te as ultrafast hole transporting layer. Benefiting from strong interlayer coupling, the Te/CdSe vdWHs exhibit stable and excellent self-powered characteristics, including ultrahigh responsivity of 0.94 A W-1, remarkable detectivity of 8.36 × 1012 Jones at optical power density of 1.18 mW cm-2 under illumination of 405 nm laser, fast response speed of 24 µs, large light on/off ratio exceeding 105, as well as broadband photoresponse (405-1064 nm), which surpass most of the reported vdWHs photodetectors. In addition, the devices display superior photovoltaic characteristics under 532 nm illumination, such as large Voc of 0.55 V, and ultrahigh Isc of 2.73 µA. These results demonstrate the construction of 2D/non-layered semiconductor vdWHs with strong interlayer coupling is a promising strategy for high-performance and low-power consumption devices.

Nonlinear All-Optical Coherent Generation and Read-Out of Valleys in Atomically Thin Semiconductors.

With conventional electronics reaching performance and size boundaries, all-optical processes have emerged as ideal building blocks for high speed and low power consumption devices. A promising approach in this direction is provided by valleytronics in atomically thin semiconductors, where light-matter interaction allows to write, store, and read binary information into the two energetically degenerate but non-equivalent valleys. Here, nonlinear valleytronics in monolayer WSe2 is investigated and show that an individual ultrashort pulse with a photon energy tuned to half of the optical band-gap can be used to simultaneously excite (by coherent optical Stark shift) and detect (by a rotation in the polarization of the emitted second harmonic) the valley population.

Multifunctional spin transport behaviors of biphenyl-molecule-based nanodevices

For the development of low-power spin-multifunctional devices, we have explored the spin-dependent transport properties of nanodevices based on zigzag graphene nanoribbons bridged respectively by oblique, horizontal, and vertical connecting biphenyl molecules. Utilizing the first-principles calculations associated with the non-equilibrium Green's function methods, we found the superb transport results demonstrate that almost 100% spin polarization exists for the obliquely connected and horizontally connected biphenyl molecules devices in the parallel state (P). All of the designed devices exhibit excellent dual spin filtering efficiency and rectification effect in the antiparallel state (AP) with the rectification ratios up to 103, 104, and 105 for obliquely, horizontally, and vertically connected model devices, respectively. Simultaneously, a pronounced negative differential resistance effect can be observed in these devices independent of the spin state. Moreover, the thermal spin transport properties of the obliquely connected model device reveal an apparent Seebeck effect. Then, the length effect on the spin-resolved transport properties for the obliquely connected device have been conducted. Results reveal that the current values are highly tunable by changing the length of obliquely connected biphenyl molecules in the P state. Meanwhile, the doual spin filtering effect still remains, but its rectification effect gradually disappears with the increasing length of center scattering region in AP state. This study provides new insights into the design of multifunctional spin carbon-based and low power consumption devices.

Recent Advanced Applications of Ionic Liquid for Future Iontronics.

Recently, electronic devices that make use of a state called the electric double layers (EDL) of ion have opened up a wide range of research opportunities, from novel physical phenomena in solid-state materials to next-generation low-power consumption devices. They are considered to be the future iontronics devices. EDLs behave as nanogap capacitors, resulting the high density of charge carriers is induced at semiconductor/electrolyte by applying only a few volts of the bias voltage. This enables the low-power operation of electronic devices as well as new functional devices. Furthermore, by controlling the motion of ions, ions can be used as semi-permanent charge to form electrets. In this article, we are going to introduce the recent advanced application of iontronics devices as well as energy harvesters making use of ion-based electrets, leading to the future iontronics research.