Flexible nanoscale high-performance FinFETs

Beyond Flexible: Unveiling the Next Era of Flexible Electronic Systems

Flexible electronics are integral in numerous domains such as wearables, healthcare, physiological monitoring, human-machine interface, and environmental sensing, owing to their inherent flexibility, stretchability, lightweight construction, and low profile. These systems seamlessly conform to curvilinear surfaces, including skin, organs, plants, robots, and marine species, facilitating optimal contact. This capability enables flexible electronic systems to enhance or even supplant the utilization of cumbersome instrumentation across a broad range of monitoring and actuation tasks. Consequently, significant progress has been realized in the development of flexible electronic systems. This study begins by examining the key components of standalone flexible electronic systems-sensors, front-end circuitry, data management, power management and actuators. The next section explores different integration strategies for flexible electronic systems as well as their recent advancements. Flexible hybrid electronics, which is currently the most widely used strategy, is first reviewed to assess their characteristics and applications. Subsequently, transformational electronics, which achieves compact and high-density system integration by leveraging heterogeneous integration of bare-die components, is highlighted as the next era of flexible electronic systems. Finally, the study concludes by suggesting future research directions and outlining critical considerations and challenges for developing and miniaturizing fully integrated standalone flexible electronic systems.

Reliability Study of Metal-Oxide Semiconductors in Integrated Circuits

This paper is devoted to the study of CMOS IC parameter degradation during reliability testing. The paper presents a review of literature data on the issue of the reliability of semiconductor devices and integrated circuits and the types of failures leading to the degradation of IC parameters. It describes the tests carried out on the reliability of controlled parameters of integrated circuit TPS54332, such as quiescent current, quiescent current in standby mode, resistance of the open key, and instability of the set output voltage in the whole range of input voltages and in the whole range of load currents. The calculated values of activation energies and acceleration coefficients for different test temperature regimes are given. As a result of the work done, sample rejection tests have been carried out on the TPS54332 IC under study. Experimental fail-safe tests were carried out, with subsequent analysis of the chip samples by the controlled parameter quiescent current. On the basis of the obtained experimental values, the values of activation energy and acceleration coefficient at different temperature regimes were calculated. The dependencies of activation energy and acceleration coefficient on temperature were plotted, which show that activation energy linearly increases with increasing temperature, while the acceleration coefficient, on the contrary, decreases. It was also found that the value of the calculated activation energy of the chip is 0.1 eV less than the standard value of the activation energy.

Scalable and Blue Photoluminescence Emissions of (C4H9NH3)2PbBr4 2D Perovskite Fabricated by the Dip-Coating Method Using a Co-Solvent System

The improved efficiency of perovskite-related photovoltaic devices, such as light-emitting diodes (LEDs), is related to film uniformity, the compactness of each layer, and thickness. Herein, we improved the traditional single-solvent, solution-processed method and developed a co-solvent method to prepare a two-dimensional (2D) (C4H9NH3)2PbBr4 perovskite film for blue photoluminescence (PL) emissions. A poor film-forming uniformity was observed for the use of the single-solvent, dimethylformamide (DMF) method. In adding 1,2-dichlorobenzene (ODCB) of a smaller polarity to DMF, the co-solvent engineering dramatically changed the film-forming properties. Optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffractometer (XRD), and time-resolved PL (TR-PL) spectroscopy analyses confirmed that the perovskite film prepared by the co-solvent system had a good crystallinity, fewer defects, and a longer carrier lifetime. These experimental results show a simple, scalable (1.23 × 1.23 cm2), and stable reproducibility method for preparing 2D perovskite of 415 nm wavelength PL emissions that might be beneficial for the development of ultraviolet (UV) photodetectors, blue LEDs, and high-resolution displays.

Nanoscale self-assembly: concepts, applications and challenges

Self-assembly offers unique possibilities for fabricating nanostructures, with different morphologies and properties, typically from vapour or liquid phase precursors. Molecular units, nanoparticles, biological molecules and other discrete elements can spontaneously organise or form via interactions at the nanoscale. Currently, nanoscale self-assembly finds applications in a wide variety of areas including carbon nanomaterials and semiconductor nanowires, semiconductor heterojunctions and superlattices, the deposition of quantum dots, drug delivery, such as mRNA-based vaccines, and modern integrated circuits and nanoelectronics, to name a few. Recent advancements in drug delivery, silicon nanoelectronics, lasers and nanotechnology in general, owing to nanoscale self-assembly, coupled with its versatility, simplicity and scalability, have highlighted its importance and potential for fabricating more complex nanostructures with advanced functionalities in the future. This review aims to provide readers with concise information about the basic concepts of nanoscale self-assembly, its applications to date, and future outlook. First, an overview of various self-assembly techniques such as vapour deposition, colloidal growth, molecular self-assembly and directed self-assembly/hybrid approaches are discussed. Applications in diverse fields involving specific examples of nanoscale self-assembly then highlight the state of the art and finally, the future outlook for nanoscale self-assembly and potential for more complex nanomaterial assemblies in the future as technological functionality increases.

Ta2 Ni3 Se8 : 1D van der Waals Material with Ambipolar Behavior

In this study, high-purity and centimeter-scale bulk Ta₂ Ni₃ Se₈ crystals are obtained by controlling the growth temperature and stoichiometric ratio between tantalum, nickel, and selenium. It is demonstrated that the bulk Ta₂ Ni₃ Se₈ crystals could be effectively exfoliated into a few chain-scale nanowires through simple mechanical exfoliation and liquid-phase exfoliation. Also, the calculation of electronic band structures confirms that Ta₂ Ni₃ Se₈ is a semiconducting material with a small bandgap. A field-effect transistor is successfully fabricated on the mechanically exfoliated Ta₂ Ni₃ Se₈ nanowires. Transport measurements at room temperature reveal that Ta₂ Ni₃ Se₈ nanowires exhibit ambipolar semiconducting behavior with maximum mobilities of 20.3 and 3.52 cm² V^-1 s^-1 for electrons and holes, respectively. The temperature-dependent transport measurement (from 90 to 295 K) confirms the carrier transport mechanism of Ta₂ Ni₃ Se₈ nanowires. Based on these characteristics, the obtained 1D vdW material is expected to be a potential candidate for additional 1D materials as channel materials.

Recent Progress in Electrochemical pH-Sensing Materials and Configurations for Biomedical Applications

pH-sensing materials and configurations are rapidly evolving toward exciting new applications, especially those in biomedical applications. In this review, we highlight rapid progress in electrochemical pH sensors over the past decade (2008-2018) with an emphasis on key considerations, such as materials selection, system configurations, and testing protocols. In addition to recent progress in optical pH sensors, our main focus in this review is on electromechanical pH sensors due to their significant advances, especially in biomedical applications. We summarize developments of electrochemical pH sensors that by virtue of their optimized material chemistries (from metal oxides to polymers) and geometrical features (from thin films to quantum dots) enable their adoption in biomedical applications. We further present an overview of necessary sensing standards and protocols. Standards ensure the establishment of consistent protocols, facilitating collective understanding of results and building on the current state. Furthermore, they enable objective benchmarking of various pH-sensing reports, materials, and systems, which is critical for the overall progression and development of the field. Additionally, we list critical issues in recent literary reporting and suggest various methods for objective benchmarking. pH regulation in the human body and state-of-the-art pH sensors (from ex vivo to in vivo) are compared for suitability in biomedical applications. We conclude our review by (i) identifying challenges that need to be overcome in electrochemical pH sensing and (ii) providing an outlook on future research along with insights, in which the integration of various pH sensors with advanced electronics can provide a new platform for the development of novel technologies for disease diagnostics and prevention.

High-performance flexible metal-on-silicon thermocouple

We have demonstrated metal-on-silicon thermocouples with a noticeably high Seebeck coefficient and an excellent temperature-sensing resolution. Fabrication of the thermocouples involved only simple photolithography and metal-liftoff procedures on a silicon substrate. The experimentally measured Seebeck coefficient of our thermocouple was 9.17 × 10-4 V/°K, which is 30 times larger than those reported for standard metal thin-film thermocouples and comparable to the values of alloy-based thin-film thermocouples that require sophisticated and costly fabrication processes. The temperature-voltage measurements between 20 to 80 °C were highly linear with a linearity coefficient of 1, and the experimentally demonstrated temperature-sensing resolution was 0.01 °K which could be further improved up to a theoretical limit of 0.00055 °K. Finally, we applied this approach to demonstrate a flexible metal-on-silicon thermocouple with enhanced thermal sensitivity. The outstanding performance of our thermocouple combined with an extremely thin profile, bending flexibility, and simple, highly-compatible fabrication will proliferate its use in diverse applications such as micro-/nanoscale biometrics, energy management, and nanoscale thermography.

CMOS Enabled Microfluidic Systems for Healthcare Based Applications

With the increased global population, it is more important than ever to expand accessibility to affordable personalized healthcare. In this context, a seamless integration of microfluidic technology for bioanalysis and drug delivery and complementary metal oxide semiconductor (CMOS) technology enabled data-management circuitry is critical. Therefore, here, the fundamentals, integration aspects, and applications of CMOS-enabled microfluidic systems for affordable personalized healthcare systems are presented. Critical components, like sensors, actuators, and their fabrication and packaging, are discussed and reviewed in detail. With the emergence of the Internet-of-Things and the upcoming Internet-of-Everything for a people-process-data-device connected world, now is the time to take CMOS-enabled microfluidics technology to as many people as possible. There is enormous potential for microfluidic technologies in affordable healthcare for everyone, and CMOS technology will play a major role in making that happen.

New strategies for producing defect free SiGe strained nanolayers

Strain engineering is seen as a cost-effective way to improve the properties of electronic devices. However, this technique is limited by the development of the Asarro Tiller Grinfeld growth instability and nucleation of dislocations. Two strain engineering processes have been developed, fabrication of stretchable nanomembranes by deposition of SiGe on a sacrificial compliant substrate and use of lateral stressors to strain SiGe on Silicon On Insulator. Here, we investigate the influence of substrate softness and pre-strain on growth instability and nucleation of dislocations. We show that while a soft pseudo-substrate could significantly enhance the growth rate of the instability in specific conditions, no effet is seen for SiGe heteroepitaxy, because of the normalized thickness of the layers. Such results were obtained for substrates up to 10 times softer than bulk silicon. The theoretical predictions are supported by experimental results obtained first on moderately soft Silicon On Insulator and second on highly soft porous silicon. On the contrary, the use of a tensily pre-strained substrate is far more efficient to inhibit both the development of the instability and the nucleation of misfit dislocations. Such inhibitions are nicely observed during the heteroepitaxy of SiGe on pre-strained porous silicon.

Role of Graphene in Reducing Fatigue Damage in Cu/Gr Nanolayered Composite

Nanoscale metal/graphene nanolayered composite is known to have ultrahigh strength as the graphene effectively blocks dislocations from penetrating through the metal/graphene interface. The same graphene interface, which has a strong sp2 bonding, can simultaneously serve as an effective interface for deflecting the fatigue cracks that are generated under cyclic bendings. In this study, Cu/Gr composite with repeat layer spacing of 100 nm was tested for bending fatigue at 1.6% and 3.1% strain up to 1,000,000 cycles that showed for the first time a 5-6 times enhancement in fatigue resistance compared to the conventional Cu thin film. Fatigue cracks that are generated within the Cu layer were stopped by the graphene interface, which are evidenced by cross-sectional scanning electron microscopy and transmission electron microscopy images. Molecular dynamics simulations for uniaxial tension of Cu/Gr showed limited accumulation of dislocations at the film/substrate interface, which makes the fatigue crack formation and propagation through thickness of the film difficult in this materials system.

Deterministic Integration of Out-of-Plane Sensor Arrays for Flexible Electronic Applications

A design strategy for fully flexible electrode arrays with out-of-plane through polymer vias (TPVs) for monolithic 3D integration of sensor readout circuitry is presented. The TPVs are formed using copper embedded in thin polyimide structure for support. The copper interconnects offer a stable impedance frequency response from DC to 100 kHz (Z ≈ 20 Ω, θ ≈ 0°).

Simultaneous Roll Transfer and Interconnection of Flexible Silicon NAND Flash Memory

Ultrathin silicon-based flexible 16 × 16 NAND flash memory (f-NAND) is demonstrated utilizing roll-to-plate packaging. The roll-based thermo-compression bonding of the anisotropic conductive film (ACF) transfers and simultaneously interconnects the f-NAND on a flexible printed circuit board. Reliable circuitry operation of the 16 × 16 f-NAND is confirmed with excellent flexibility and stable ACF interconnections.

CMOS-Technology-Enabled Flexible and Stretchable Electronics for Internet of Everything Applications

Flexible and stretchable electronics can dramatically enhance the application of electronics for the emerging Internet of Everything applications where people, processes, data and devices will be integrated and connected, to augment quality of life. Using naturally flexible and stretchable polymeric substrates in combination with emerging organic and molecular materials, nanowires, nanoribbons, nanotubes, and 2D atomic crystal structured materials, significant progress has been made in the general area of such electronics. However, high volume manufacturing, reliability and performance per cost remain elusive goals for wide commercialization of these electronics. On the other hand, highly sophisticated but extremely reliable, batch-fabrication-capable and mature complementary metal oxide semiconductor (CMOS)-based technology has facilitated tremendous growth of today's digital world using thin-film-based electronics; in particular, bulk monocrystalline silicon (100) which is used in most of the electronics existing today. However, one fundamental challenge is that state-of-the-art CMOS electronics are physically rigid and brittle. Therefore, in this work, how CMOS-technology-enabled flexible and stretchable electronics can be developed is discussed, with particular focus on bulk monocrystalline silicon (100). A comprehensive information base to realistically devise an integration strategy by rational design of materials, devices and processes for Internet of Everything electronics is offered.

Nonplanar Nanoscale Fin Field Effect Transistors on Textile, Paper, Wood, Stone, and Vinyl via Soft Material-Enabled Double-Transfer Printing

The ability to incorporate rigid but high-performance nanoscale nonplanar complementary metal-oxide semiconductor (CMOS) electronics with curvilinear, irregular, or asymmetric shapes and surfaces is an arduous but timely challenge in enabling the production of wearable electronics with an in situ information-processing ability in the digital world. Therefore, we are demonstrating a soft-material enabled double-transfer-based process to integrate flexible, silicon-based, nanoscale, nonplanar, fin-shaped field effect transistors (FinFETs) and planar metal-oxide-semiconductor field effect transistors (MOSFETs) on various asymmetric surfaces to study their compatibility and enhanced applicability in various emerging fields. FinFET devices feature sub-20 nm dimensions and state-of-the-art, high-κ/metal gate stacks, showing no performance alteration after the transfer process. A further analysis of the transferred MOSFET devices, featuring 1 μm gate length, exhibits an ION value of nearly 70 μA/μm (VDS = 2 V, VGS = 2 V) and a low subthreshold swing of around 90 mV/dec, proving that a soft interfacial material can act both as a strong adhesion/interposing layer between devices and final substrate as well as a means to reduce strain, which ultimately helps maintain the device's performance with insignificant deterioration even at a high bending state.