Good Switching Performance Research Articles

Active logic modulator of terahertz metamaterial for future 6G communication system

A tunable G-shaped metamaterial (GSM) for the upcoming 6G communication system is presented. GSM device shows polarization-dependent characteristics with three or five resonances. The GSM unit cell is composed of two identical G-shaped structures on a silicon (Si) substrate. By utilizing micro-electro-mechanical system (MEMS) technology to change the vertical height (h) between the two G-shaped structures and the horizontal distance (g) between them or change the polarization angle (PA) of the incident light, the electromagnetic responses of GSM device can be switched three to five resonances. The tuning range of resonant frequency of the GSM device is up to 15 GHz by changing the g value, and the modulation depth can reach 93 % by changing PA and h values. This MEMS-based GSM device exhibits multi-resonance and polarization-dependent characteristics, offering an efficient and economical way to modulate terahertz (THz) signals. Moreover, the GSM device also exhibits good optical switching performance at PA = 0°, 30°, and 75° under the condition of h = 2 μm. These characteristics can be expressed as logic signals 'ON' and 'OFF' states, enabling their application in the logic operation function of the NAND gate and programmable two-bit binary digital coding metamaterials.

Structure, Characterizations, Photocurrent Response, and Theoretical Study of One Chained Hybrid Iodoplumbate

AbstractExploring new haloplumbate hybrids and understanding the structure‐activity relationships are of great significance for further promoting their applications in the photovoltaic fields. Herein, with the in situ‐formed [Hmd]+ (md = 2‐methyl‐1,3‐diazinane) templates, a new organic–inorganic hybrid iodoplumbate, namely [Hmd]PbI3 (1), is successfully constructed and then structurally characterized using multiple technical approaches. X‐ray crystallography studies show that compound 1 features the typical 1D chain‐like motifs of [Pb2I6]n2n−, generating the 3D supermolecular network by the extensive hydrogen bond interactions. Interestingly, compound 1 exhibits the semiconductive behavior, with an optical band gap of 2.72 eV. More attractively, the title compound has good photoelectric switching performances under the alternating light irradiation, whose photocurrent densities compete well with or surpass those of many metal halide counterparts. Further theoretical analyses reveal that the title compound has a more dispersive band structure (especially the value band) that facilitates the transport of charge carriers, which may be the main origin of its excellent optoelectronic performance. Presented in this paper also bring the studies of Hirshfeld surface, X‐ray photoelectron spectroscopy (XPS) as well as thermogravimetric analysis.

Enabling low-power analog and RFIC design through advanced semiconductor FDSOI MOSFETs

This study investigates the electrical performance of advanced semiconductor Ge-pocket-doped fully depleted silicon-on-insulator MOSFETs in comparison to conventional fully depleted silicon-on-insulator (FDSOI) MOSFETs. In this study vital electrical parameters such as the drain current, band diagram, lateral electric field, surface potential, and work function of the gate material were investigated. The advanced Ge pocket-doped FDSOI MOSFET structure demonstrates superior characteristics, such as a higher Ion/Ioff ratio, smaller subthreshold slope, lower capacitance, and higher cut-off frequency, when compared to conventional FDSOI MOSFETs. The structure of the Ge pocket-doped FDSOI MOSFET in the source and drain regions is designed to overcome the scaling effects of the transistor. In addition, this paper delves into the fabrication of the proposed device structure, outlining the key steps and intricacies involved. This study shows that the proposed device can be used for both digital and analog applications because it has good switching performance and a low cut-off frequency. In addition, the fabrication steps of the proposed structure were compatible with the existing fabrication process steps for conventional FDSOI MOSFETs. The simulation and analysis of the advanced semiconductor structure were performed using the Sentaurus TCAD simulator.

Toward Sustainability in All‐Printed Accumulation Mode Organic Electrochemical Transistors

AbstractThis study reports on the first all‐printed vertically stacked organic electrochemical transistors (OECTs) operating in accumulation mode; the devices, relying on poly([4,4′‐bis(2‐(2‐(2‐methoxyethoxy)ethoxy)ethoxy)‐2,2′‐bithiophen‐5,5′‐diyl]‐alt‐[thieno[3,2‐b]thiophene‐2,5‐diyl]) (pgBTTT) as the active channel material, are fabricated via a combination of screen and inkjet printing technologies. The resulting OECTs (W/L ≈5) demonstrate good switching performance; gm, norm ≈13 mS cm−1, µC* ≈21 F cm−1 V−1 s−1, ON–OFF ratio > 104 and good cycling stability upon continuous operation for 2 h. The inkjet printing process of pgBTTT is established by first solubilizing the polymer in dihydrolevoglucosenone (Cyrene), a non‐toxic, cellulose‐derived, and biodegradable solvent. The resulting ink formulations exhibit good jettability, thereby providing reproducible and stable p‐type accumulation mode all‐printed OECTs with high performance. Besides the environmental and safety benefits of this solvent, this study also demonstrates the assessment of how the solvent affects the performance of spin‐coated OECTs, which justifies the choice of Cyrene as an alternative to commonly used harmful solvents such as chloroform, also from a device perspective. Hence, this approach shows a new possibility of obtaining more sustainable printed electronic devices, which will eventually result in all‐printed OECT‐based logic circuits operating in complementary mode.

Three Iodoargentate-Based Hybrids Decorated by Metal Complexes: Structures, Optical/Photoelectric Properties and Theoretical Studies.

So far, the development of new iodoargentate-based hybrids, especially those compounds with metal complex cations, and the understanding of their structure-activity relationships have been of vital importance but full of challenges. Herein, using the in-situ-generated metal complex cations as structural directing agents, three new iodoargentate-based hybrids, namely, [Co(phen)3]Ag2PbI6 (phen = 1,10-phenanthroline; 1), [Ni(5,5-dmpy)3]Ag7I9·CH3CN (5,5-dmpy = 5,5-dimethyl-2,2-bipyridine; 2) and [Co(5,5-dmpy)3]Ag5I8 (3), have been solvothermally prepared and then structurally characterized. Compound 1 represents one new heterometallic Ag-Pb-I compound characteristic of the chain-like [Ag2PbI6]n2n- anions. Compound 2 features the straight one-dimensional (1D) [Ag7I9]n2n- anionic moieties, while compound 3 contains infrequent two types of curved [Ag5I8]n3n- anions. Optical properties reveal that the title compounds exhibit interesting semiconductor behaviors with the band gaps of 1.59-2.78 eV, which endow them with good photoelectric switching performances under the alternate light irradiations. We also present their Hirshfeld surface analyses, and the theoretical studies (band structures, density of states (DOS) and partial density of states (PDOS)).

High-performance dual-tunable terahertz absorber based on strontium titanate and bulk Dirac semimetal for temperature sensing andswitching function.

In this study, a perfect metamaterial absorber based on strontium titanate and bulk Dirac semimetals is proposed. When the temperature of strontium titanate was 300K, the dual-band absorptions were 99.74% and 99.99% at 1.227 and 1.552THz, respectively. The sensitivities based on a transverse magnetic (TM) wave were 0.95 and 1.22GHz/K; the sensitivity based on a transverse electric (TE) wave was 0.76GHz/K. The TE and TM waves were modulated by inserting a bulk Dirac semimetal between the concave and convex devices. The modulation depth of the TE wave was 97.9% at 1.1THz; the extinction ratio was 16.9dB. The modulation depth of the TE wave at 1.435THz was 95.9%; the extinction ratio was 13.89dB. The TM wave modulation depth at 1.552THz was 95.9%; the extinction ratio was 13.98dB. Irrespective of a TE or TM wave, the terahertz absorber has good switching and temperature-sensing performance based on strontium titanate and bulk Dirac semimetals as well as broad application prospects in temperature sensing and switching devices.

Thermally Stable and High-Speed Ge-Te Based Ovonic Threshold Switching Selector With a Ge Intercalated Structure

Thermal stability and switching speed of ovonic threshold switching (OTS) selector are key elements for its high-speed memory application. However, current methods tend to introduce over complicated elements and even toxic elements which will improve fabrication process complexity and be environment unfriendly. In this work, we studied a Ge-Te based OTS selector with Ge intercalated layers inserted in OTS layer. Through Poole-Frenkel model fitting, we found that the Ge intercalated layers introduced energy barrier, reducing device off-current while improving its thermal stability. The optimized device showed a thermal stability improvement of more than 180°C. In the meantime, the optimized device had good switching performance with fast switching speed of 8.2 ns, low off-current of 10 nA, and endurance of 1.3×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> . After a 350°C annealed process, the device performance showed good uniformity and almost no degradation. This work provides experiment guidance of the high thermal stability requirement for OTS selectors.

Simultaneously elevating the resistive switching performance and thermal/irradiative stabilities of biomemorizer based on twisted carboxylated multi-walled carbon nanotube-chitosan composites

Bio-resistive memory devices with good environmental robustness are important for the next generation of biodegradable electronic devices. In this field, the facile achievement of both resistive switching performance and environmental robustness is still challengeable. Herein, resistive switching active oxidized multi-walled carbon nanotube (O-MWCNT) has been doped into chitosan (CS) to produce twisted O-MWCNT-CS biocomposites based on strong -COO-/NH3+ electrostatic interaction. The FTO/O-MWCNT-CS(8%)/Ag biomemorizer can exhibit good resistive switching performance with high ON/OFF ratio (104.51) and low setting voltage (0.86 V). Besides, this biomemorizer possesses good environmental robustness with thermal (200 °C) and ionizing irradiation tolerance (UV exposure for 72 h). Ag conductive filament formation and rupture account for the resistive switching behavior. Specially, the conduction pathways provided by O-MWCNT and its good radical scavenging ability are the reason for the facile realization of resistive switching performances even under large layer thickness. The facile carboxylation on MWCNT and robust O-MWCNT-CS biocompoiste together with good environmental robustness render the promising applications as green, stable and biodegradable electronic devices.

Failure mechanism investigation and endurance improvement in Te-rich Ge–Te based ovonic threshold switching selectors

The endurance of ovonic threshold switching (OTS) selectors is a key element for memory application. However, multi-element system for OTS in recent studies will induce element or phase segregation and lead to device failure. Since pure Te based device characterizes relatively high off current, in this work, we studied a Te-rich Ge–Te based OTS selector. We first conducted a failure analysis on Ge–Te based OTS selector. Through first-principles calculations, we found that a relatively larger Ge concentration in the Ge–Te system may lead to a worse device endurance after continuous operation due to the migration of Ge atoms. Experiments further proved that device endurance can be improved more than two orders of magnitude through decreasing Ge concentration and the element segregation is greatly weakened by the composition close to elemental. Finally, a significantly improved endurance of 2 × 1010 was realized in Ge10Te90 based OTS selectors. In the meantime, the Ge10Te90 based OTS selectors show good switching performance and potential for use in memory applications.

Ab initio quantum transport simulations of monolayer GeS nanoribbons

Monolayer germanium monosulfide (GeS) was recently identified as one of the most promising 2D materials for ultra-scaled FETs. While sub-10 nm monolayer GeS FETs were studied by quantum transport, very little is known about GeS nanoribbons (GeSNRs) or GeSNR FET performance. In this work, we employ quantum transport and Hamiltonians with an orbital resolution to study the electronic, transport, and ballistic device properties of sub-4 nm-wide and ∼15 nm-long GeSNRs. While ultra-scaled GeSNR FETs exhibit ION/IOFF of at least ∼7×105, indicating good switching performance, they also offer modest ballistic ION values of up to ∼1.2 mA/μm.

Electrical Life of Vacuum Interrupters for Load Current Switching

While the short-circuit current of vacuum interrupters (VIs) is a key performance parameter, very high current operations rarely occur in actual applications. In contrast, switching load and/or capacitive currents comprise virtually all the practical operations. Load current switching requires a low contact erosion and low metal vapor generation of the arc to achieve a long electrical life and is achieved by contacts in vacuum. However, the excellent performance of contacts in vacuum makes the testing and determination of the ultimate electrical life at load currents challenging. Tests on Cu–Cr and Cu–W contacts in VIs were performed at 2500–2700 A rms with 20 000–30 000 switching operations. The VIs with both types of contacts retained their dielectric strength, contact shape and composition, and low contact resistance. Even after arcing operations with total transferred charges >200 kA <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula> s per interrupter, the contacts could continue providing good dielectric and switching performance with low resistance. Contact erosion was minimal and of limited practical significance. These results demonstrate the very long electrical life of VIs when the vacuum arc is naturally diffuse.

Impact of local atomic arrangements on ovonic threshold switching of amorphous Ge-As-Se thin films

Amorphous Ge-As-Se film features a good ovonic threshold switching (OTS) performance. However, both endurance of OTS operation and crystallization temperature become dramatically deteriorated at specific compositions. We employ EXAFS technique to elucidate local atomic environments in cosputter-deposited amorphous (Ge50Se50)x-(Ge30As70)1-x films. At low Se contents, Se atoms are preferentially bonded to Ge atoms, and therefore Ge-Se fraction is conspicuously higher than As-Se counterpart. A covalent network structure typical of amorphous chalcogenides is supposed to form. At high Se contents, however, As-Se pair starts to abruptly increase at the expense of As-Ge fraction. Now verified in these high-Se compositions is appearance of molecular units composed of As and Se atoms, i.e., As4Se4 and/or As4Se3. The sudden deterioration is attributed to presence of the molecular units which lower connectivity of the covalent network via introducing inhomogeneity in a medium-range scale. The present finding exemplifies impact of local atomic arrangements on OTS phenomenon.

Impact of channel mobility on design optimization of 600–3300 V-class high-speed GaN vertical-trench MOSFETs based on TCAD simulation

To simultaneously evaluate the switching performance and cost (required chip size) of GaN vertical-trench metal-oxide-semiconductor field-effect transistors, we calculated R on AR on Q g considering the Miller effect with various cell pitches, channel mobilities, and blocking voltages. When the blocking voltage was 600 V, optimized cell pitches of 8 and 12 μm minimized R on AR on Q g with channel mobilities of 100 and 200 cm2 V−1 s−1, respectively. Moreover, a wide range of cell pitches could maintain a low R on AR on Q g with a channel mobility of 200 cm2 V−1 s−1. This indicates that a channel mobility of 100 cm2 V−1 s−1 or higher, particularly 200 cm2 V−1 s−1, is desirable for a good switching performance and low cost.

Investigation of the Resistive Switching Mechanisms and Rectification Characteristics of HfO₂-Based Resistive Random Access Memory Devices with Different Electrode Materials.

To study the substitutability of noble metal electrodes in memristors, the effect of Pt/HfO₂/Ti structure on the replacement of noble metal electrode Pt by different electrodes was studied. Compared with the unsubstituted devices, the HfO₂-based RRAM devices with TiN and TiOxNy electrodes devices showed good resistive switching performance and resistive switching mechanism under oxygen ion migration. Five devices were prepared, and their resistive switching mechanism under oxygen ion migration was investigated. Moreover, besides the resistive switching phenomenon of these RRAM devices, it was found that significant rectifying characteristics were exhibited in a highresistance state (HRS). This phenomenon can be explained by regulation of the Schottky barrier of the interface between the top electrode and the resistive layer, which can be influenced by the migration of oxygen vacancies.

Thickness regulates the ferroelectric and resistance switching properties of BiFeO3 (Nia/Nib) superlattice films

Bi0.89Ho0.08Sr0.03Fe0.97-aMn0.03NiaO3/Bi0.89Ho0.08Sr0.03Fe0.97-bMn0.03NibO3 (Nia/Nib) superlattice films were prepared by the sol–gel successfully. The influence of the change of the thickness of the superlattice films on the multiferroic and resistance switching properties were studied. It shows that due to the reduction of internal stress, the thin Nia/Nib superlattice films make the layer interface effect enhance to get more the interface charges, which improves the efficiency of the interaction between the interface charges, thereby obtaining good resistance switching (RS) performances. However, the thick Nia/Nib superlattice films improved the ferroelectricity due to the smaller layer interface effect. It indicates that changing the thickness of the single layer of the superlattice film is beneficial to the regulation of the properties of the films. Eventually, the different applications of BiFeO3 film in modern microelectronic devices can be realized by adjusting the thickness of the superlattice film.

Design of Semiconductor Synchronous Buck Converter based on GaNWide-bandgap

Aiming at the limited switching frequency of traditional silicon (Si) based devices and its huge switching loss when working under the high-frequency conditions, this paper proposes a synchronous buck converter based on GaN power devices with good switching performance and low loss. In this paper, the detailed parameter design method and simulation circuit were given. This paper also conducts thermal stability analysis. Finally, the simulation experiment proves the feasibility and effectiveness of this theory.

Electro-optical effect and optical absorption in (K,Na)NbO3-based piezoceramics

The intriguing coupling interactions between photochromism and ferroelectric polarization were firstly observed in Sm doped (K0.5Na0.5)NbO3 piezoceramics. After 407 nm irradiation, the maximum polarization (Pmax) and remanent polarization (Pr) intensities were dramatically decreased, whereas the coercive field, leakage current and photocurrent showed the remarkable increase. The variations of the polarization and photocurrent can be reversibly converted by alternating light irradiation and thermal stimulus, suggesting good polarization switching performance. This work provides a new route to effectively modulate ferro-/piezoelectric and photocurrent properties of ferroelectric materials by the non-contact remote control of light.

An active carbon-nanotube polarizer-embedded electrode and liquid-crystal alignment.

We report a method for constructing an active optical polarizer using an aligned carbon nanotube (CNT) sheet that is flexible, bendable, transparent, conductive, and also serves to anchor liquid-crystal (LC) molecules. A horizontally aligned CNT sheet was obtained by mechanical stretching from a vertically grown CNT forest, which was then transferred onto a substrate. A liquid polymer was infiltrated into the CNT sheet followed by UV curing, while a part of the CNT sheet was still exposed on the film surface without polymer coating. The polymer-embedded CNT sheet (P-ECS) film with 10 layers of CNT sheets exhibited a good polarization efficiency of 87%, a sheet resistance of 340 Ω□-1, and excellent ability to align LC molecules. The high stability of the P-ECS film was confirmed from the very low variation of sheet resistance (2%) and transmittance (10%) observed during a bending test of 1000 cycles. In addition, a twisted nematic LC device constructed using the P-ECS films shows a good bright-dark switching performance. The P-ECS film functions simultaneously as a transparent electrode, a film-type polarizer, and a LC alignment layer, demonstrating the multi-functionality of the active CNT film. This study thus highlights a wide range of possible applications for active polarizers and flexible displays.

Printed Flexible Organic Transistors with Tunable Aspect Ratios

AbstractA fabrication technique that allows aspect ratio modulation in a large array of organic thin film transistors (OTFTs) is demonstrated. In this design, discrete interdigitated source and drain electrodes can be individually selected to create a range of aspect ratios (W/L). It is shown that by increasing the aspect ratio, the drain current is increased respectively. Arrays of OTFTs are fabricated with a combination of inkjet printing and surface energy patterned blade coating. OTFTs with optimized aspect ratios are interconnected to form electronic circuits with the desired performance. A fabricated enhancement‐load inverter with selected aspect ratios of 2000 µm/50 µm for the drive OTFT and 250 µm/50 µm for the load transistor show good switching performance with a dc gain of approximately 6 at supply voltage of −20 V.

Conjugated polymer nanoparticles as fluorescence switch for selective cell imaging

Fluorescence switch plays a vital role in bioelectronics and bioimaging. Herein, we presented a new kind of facile electrostatic complex nanoparticles (ECNs) for fluorescence switching in cells and marking of individual cell. The ECNs were prepared by mixing positively charged poly(6-(2-(thiophen-3-yl)ethoxy)hexyl trimethylammonium bromide) (PT) and negatively charged diarylethene sodium salt (DAE-COONa). DAE-COONa is a photoswitchable molecule which can be transformed between the ring-closed form and ring-open form under the irradiation of UV or visible light. The closed-form of DAE-COONa can efficiently quench the fluorescence of PT through intermolecular energy transfer, while the open form of DAE-COONa does not influence the emission of PT. Thus, the fluorescence of ECNs can be modulated by light irradiation, and the ECNs with good fluorescence switching performance have been employed for fluorescence imaging and individual cell lighting up process successfully. We demonstrate that the electrostatic complex strategy provides a facile method to construct fluorescence switch for selective cell marking and imaging applications.