Well-Balanced Ambipolar Charge Transport of Diketopyrrolepyrrole-Based Copolymers: Organic Field-Effect Transistors and High-Voltage Logic Applications.

A poly (3,6-bis(thiophen-2-yl)-2,5-bis(2-decyltetradecyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione-co-(2,3-bis(phenyl)acrylonitrile)) (PDPADPP) copolymer, composed of diketopyrrolopyrrole (DPP) and a cyano (nitrile) group with a vinylene spacer linking two benzene rings, is synthesized via a palladium-catalyzed Suzuki coupling reaction. The electrical performance of PDPADPP in organic field-effect transistors (OFETs) and circuits is investigated. The OFETs based on PDPADPP exhibit typical ambipolar transport characteristics, with the as-cast OFETs demonstrating low field-effect hole and electron mobility values of 0.016 and 0.004 cm2  V-1  s-1 , respectively. However, after thermal annealing at 240 °C, the OFETs exhibit improved transport characteristics with highly balanced ambipolar transport, showing average hole and electron mobility values of 0.065 and 0.116 cm2  V-1  s-1 , respectively. To verify the application of the PDPADPP OFETs in high-voltage logic circuits, compact modeling using the industry-standard small-signal Berkeley short-channel IGFET model (BSIM) is performed, and the logic application characteristics are evaluated. The circuit simulation results demonstrate excellent logic application performance of the PDPADPP-based ambipolar transistor and illustrate that the device annealed at 240 °C exhibits ideal circuit characteristics.

Variability-Aware Simulation Strategy for Gate-All-Around Vertical Field Effect Transistor.

In this work, the work function variation (WFV) and global variability (GV) sources on 5 nm node gate-all-around (GAA) silicon vertical field-effect transistor (VFET) devices are studied through technology computer-aided design (TCAD) simulations and spice simulation based on BSIM-CMG model. Compared to conventional lateral FET devices, VFETs can increase the gate area effectively while minimizing the loss of layout area due to their structural characteristics. Considering VFET devices below 5 nm node, an expansion of the gate area of the device reduces the influence of WFV. However, the effect of GV is exacerbated by weakening gate controllability. In order to analyze the exact variability issues, it is necessary to consider not only the influence by the WFV but also the influence by the GV. Therefore, we propose accurate guideline by analyzing the integrated variability issues in a various VFET device structures in a single device and a 6-T SRAM bit cells.

Effect of Various Geometry Parameters on the Performance of Nanoplate Field Effect Transistor with Negative Capacitance.

In this paper, we investigate the impact of geometry parameters such as ferroelectric layer thickness (TFE), extension length (LExt), overlap length (Lov) on negative capacitance FET (NCFET). The NCFET is designed using HfZrO2 (HZO) ferroelectric materials and the Nanoplate FET (NPFET) presented as a next generation device. We use the 3-D TCAD Sentaurus simulator to analyze characteristics of the NCFET. The NCFET designed considering the stable condition overcomes the Boltzmann limit (i.e., the physical limit in the S.S., which is 60 mV/decade at 300 K) through the steep subthreshold swing (S.S.) and exhibits negative Drain-induced barrier lowering (DIBL) phenomenon. When examining the characteristics of NPFET and NCFET according to LExt and Lov, the NCFET exhibits gate capacitance (Cgg) tendency opposite to that of the NPFET. The NCFET with the scaled VDD has a significant advantage over the gate delay (τd). The NCFET has better performance in environments where conventional device is more vulnerable to short channel effects (SCEs).

Device Optimization of Nano-Plate Transistors for 3.5 nm Technology Node.

In this paper, lateral gate-all-around nano-plate transistors (NP-FETs) for 3.5 nm technology node were optimized and compared with other nodes such as 7 nm and 5 nm node devices. The transistors' electrostatic was analyzed using a 3D TCAD simulation. We firstly optimized physical parameters such as channel radius and thickness. The NP-FETs for 3.5 nm node had better gate controllability due to smaller channel thickness and therefore showed an advantage in subthreshold swing (S.S.). However, parasitic resistance and capacitance, and low bias condition of scaled device lowered on-current level. These problems of smaller device were also related to limitation of RC-delay performance. Accordingly, the scaled device with optimized physical parameters showed ~1% decrease in delay performance compared to 5 nm node device. In order to improve RC-delay performance, trenched contact method and channel strain engineering method were separately applied for the same device. For each engineering technique, the on-current boosting was successful, showing ~14% faster RC-delay performance with strain engineering and ~18% faster RC-delay with trenched contact method.

Analysis of Variation and Ferroelectric Layer Thickness on Negative Capacitance Nanowire Field-Effect Transistor.

We investigate the interrelation between some variations and the stability of Negative Capacitance Field-Effect Transistors (NC FETs). When a variation effect is considered, stability issues which are making hysteretic operation should be considered for NC FETs as well. In this paper, to make sure of stability and hysteresis-free operation, a thickness margin of ferroelectric layer is suggested. It is the easiest solution for designing and surest method of vouching for hysteresis-free operation. Although some disadvantages which make subthreshold swing (SS) a bit higher than without a margin on thickness of ferroelectric layer (TFE) can be caused, both still high performance and stable operation can be achieved.

Repurposing compact discs as master molds to fabricate high-performance organic nanowire field-effect transistors.

Organic field-effect transistors (OFETs) have been developed over the past few decades due to their potential applications in future electronics such as wearable and foldable electronics. As the electrical performance of OFETs has improved, patterning organic semiconducting crystals has become a key issue for their commercialization. However, conventional soft lithographic techniques have required the use of expensive processes to fabricate high-resolution master molds. In this study, we demonstrated a cost-effective method to prepare nanopatterned master molds for the fabrication of high-performance nanowire OFETs. We repurposed commercially available compact discs (CDs) as master molds because they already have linear nanopatterns on their surface. Flexible nanopatterned templates were replicated from the CDs using UV-imprint lithography. Subsequently, 6,13-bis-(triisopropylsilylethynyl) pentacene nanowires (NWs) were grown from the templates using a capillary force-assisted lithographic technique. The NW-based OFETs showed a high average field-effect mobility of 2.04 cm2 V-1 s-1. This result was attributed to the high crystallinity of the NWs and to their crystal orientation favorable for charge transport.

An Aspect of the History of Medicine in Ancient Korea as Examined through Silla Buddhist Monks'Annotations on the "Chapter on Eliminating Disease"in the Sutra of Golden Light (Suvarnabhasa-sutra).

Nearly nothing is known of medicine in ancient Korea due to insufficient materials. With several extant prescriptions and esoteric methods of treating diseases alone, it is impossible to gauge in depth the management of medicine during this period. If one exception were to be cited, that would be the fact that the annotations for understanding the contents on Indian medicine in the "Chapter on Eliminating Disease" in the Sutra of Golden Light, a Buddhist sutra originating from India, reflected the medical knowledge of Buddhist monks from Silla (57 BC-935 AD) who were active immediately after the nation's unification of the two other kingdoms on the Korean Peninsula (668 AD) such as Wonhyo (617-686 AD), Gyeongheung (620?-700? AD), and Seungjang (684-? AD). Along with those by other monks, these annotations are collected in the Mysterious Pivot of the Sutra of Golden Light, which was compiled by Gangyo(835-871 AD), a Japanese monk from the Heian era (794-1185 AD). Representative versions of the "Chapter on Eliminating Disease" in the Sutra of Golden Light include: a classical Chinese translation by the Indian monk Dharmaksema (385-433 AD); the eight-volume edition by Chinese monk Baogui, which differs little from the preceding work in terms of the contents of the "Chapter on Eliminating Disease"; and the ten-volume edition by Yijing (635-713 AD), who had full-fledged knowledge of Indian medicine. When the contents of the annotations thus collected are examined, it seems that Wonhyo had not been aware of the existence of the ten-volume edition, and Gyeongheung and Seungjang most certainly used the ten-volume edition in their annotations as well. Especially noteworthy are Wonhyo's annotations on the Indian medical knowledge found in the "Chapter on Eliminating Disease" in the Sutra of Golden Light. Here, he made a bold attempt to link and understand consistently even discussions on Indian and Buddhist medicine on the basis of the traditional East Asian medical theory centering on the yin-yang and five phases (wuxing). In accordance with East Asia's theory of the seasonal five phases, Wonhyo sought to explain aspects of Indian medicine, e.g., changes in the four great elements (catvari maha-bhutani) of earth, water, fire, and wind according to seasonal factors and their effect on the internal organs; patterns of diseases such as wind (vata)-induced disease, bile (pitta)-induced disease, phlegm (slesman)-induced disease, and a combination (samnipata) of these three types of diseases; pathogenesis due to the indigestion of food, as pathological mechanisms centering on the theory of the mutual overcoming (xiangke) of the five phases including the five viscera (wuzang), five flavors (wuwei), and five colors (wuse). They existed in the text contents on Indian medicine, which could not be explicated well with the existing medical knowledge based on the theory of the five phases. Consequently, he boldly modified the theory of the five phases in his own way for such passages, thus attempting a reconciliation, or harmonization of disputes (hwajaeng), of the two medical systems. Such an attempt was even bolder than those by earlier annotators, and Wonhyo's annotations came to be accepted by later annotators as one persuasive explanation as well. In the case of Gyeongheung and Seungjang, who obtained and examined the ten-volume edition, a new classical Chinese translation produced following Wonhyo's death, annotated the "Chapter on Eliminating Disease" based on their outstanding proficiency in Sanskrit and knowledge of new Indian and Buddhist medicine. This fact signifies that knowledge of the eight arts of Ayurvedic medicine in India was introduced into Silla around the early 8th century. The medical knowledge of Wonhyo, Gyeongheung, and Seungjang demonstrates that intellectual circles in contemporary Silla were arenas in which not only traditional East Asian medicine as represented by works such as the Inner Canon of the Yellow Emperor (Huangdi Neijing) but also Indian medicine of Buddhism coexisted in almost real time.

Optical property of blended plasmonic nanofluid based on gold nanorods.

Present work experimentally characterizes the optical property of blended plasmonic nanofuids based on gold nanorod (AuNR) with different aspect ratios. The existence of localized surface plasmon resonance was verified from measured extinction coefficient of three AuNR solutions, and spectral tunability of AuNR nanofluid was successfully demonstrated in the visible and near-infrared spectral region. The representative aspect ratio and volume fraction of each sample were then calculated from the relation between extinction coefficient and extinction efficiency, which leads to the design of a blended plasmonic nanofluid having broad-band absorption characteristic in the visible and near-infrared spectral region. The results obtained from this study will facilitate the development of a novel volumetric solar thermal collectors using plasmonic nanofluids.

Characteristics of Using Oriental Medicine Clinics during the Japanese Occupation: An Analysis of the 1931 Seoul Bochun Clinic Account Book.

This article analyzes the "account book" of Kim Young-hoon (1882-1974), which summarizes information about patients at his Bochun Clinic in Seoul (then Gyeongseong) in 1931. Kim Young-hoon was a pivotal figure in the medical scene throughout the Korean Empire, the Japanese occupation, and the early years of the Republic of Korea. He left behind a large amount of documentation during his 60 years of practice at the Bochun Clinic, which he opened in the spring of 1909. In particular, the 1931 "account book" offers an insight into the daily life histories of his patients. Among the patient-visitors recorded in the account book, there were many influential people of the time, ranging from privileged individuals to anti-Japanese independence activists, from those in political and economic fields to those in academic and entertainment fields. At the same time, a significant number of lower-class people also visited the Clinic. Geographically, patients were centered in the city center of the capital, Gyeongseong, but were also widely distributed throughout the country. There are indications that those from the rural areas stayed in the homes of their acquaintances in Seoul. As such, the account book provides a tangible, concrete picture of the clinic's management for the year 1931, including visitor demographics, visiting diagnoses, telephone consultations, and the total cost of medicinal prescriptions. Because the account book is a one-year statistic, it has its limitations; however, it is the smallest unit that can be analyzed statistically. It provides insights into how many people came in over the course of a year and how much they spent. The expenditures are kept per individual family. The patient's name, prescribed medication, and the price of the medicine are mandatorily included, and in many cases, the place of residence and family relationships are also noted. The account book shows several layers of householders, servants, and employees in the extended family; it also shows people in various occupations. A few privileged families accounted for nearly half of the total expenditures, and the powerful visited frequently, utilizing Oriental medicine for many of their daily needs. For some, the Bochun Clinic is reminiscent of the royal temples of the dynasties. Patients come from the center and suburbs of Seoul, as well as from all over the country. In one year, more than one thousand types of prescriptions are issued and the total cost of medicines is about 33 seom (≒180 liters of rice). Although there is a concentration of high-frequency prescriptions, more than a thousand prescriptions are prescribed only once, which shows that the practice is specialized for each individual. Patient visits, consultations, and telephone use are observed, and the use of new drugs, quinine, and special ginseng as one-herb medication (danbang) are also noticeable. The statistical analysis of the 1931 Bochun Clinic "account book" can serve as a milestone for comparative analysis of the patterns of herbal medicine use before and after that year. Meanwhile, the Bochun Clinic "account book" shows the continuation of traditional practices of herbal medicine by both the powerful and the masses. On the one hand, Koreans responded to the coercive tide of modernity symbolized by the Imperial Governorate of Japan, but on the other hand, they were unwilling to let go of tradition and their own authority. While actively embracing the tide of civilization, Koreans also internalized their own rationality and sought to open a new path forward, a sentiment discernible between the lines of the "account book."

Analyzing Various Structural and Temperature Characteristics of Floating Gate Field Effect Transistors Applicable to Fine-Grain Logic-in-Memory Devices.

Although the von Neumann architecture-based computing system has been used for a long time, its limitations in data processing, energy consumption, etc. have led to research on various devices and circuit systems suitable for logic-in-memory (LiM) computing applications. In this paper, we analyze the temperature-dependent device and circuit characteristics of the floating gate field effect transistor (FGFET) source drain barrier (SDB) and FGFET central shallow barrier (CSB) identified in previous papers, and their applicability to LiM applications is specifically confirmed. These FGFETs have the advantage of being much more compatible with existing silicon-based complementary metal oxide semiconductor (CMOS) processes compared to devices using new materials such as ferroelectrics for LiM computing. Utilizing the 32 nm technology node, the leading-edge node where the planar metal oxide semiconductor field effect transistor structure is applied, FGFET devices were analyzed in TCAD, and an environment for analyzing circuits in HSPICE was established. To seamlessly connect FGFET-based devices and circuit analyses, compact models of FGFET-SDB and -CSBs were developed and applied to the design of ternary content-addressable memory (TCAM) and full adder (FA) circuits for LiM. In addition, depression and potential for application of FGFET devices to neural networks were analyzed. The temperature-dependent characteristics of the TCAM and FA circuits with FGFETs were analyzed as an indicator of energy and delay time, and the appropriate number of CSBs should be applied.

Oxide and 2D TMD semiconductors for 3D DRAM cell transistors.

As the downscaling of conventional dynamic random-access memory (DRAM) has reached its limits, 3D DRAM has been proposed as a next-generation DRAM cell architecture. However, incorporating silicon into 3D DRAM technology faces various challenges in securing cost-effective high cell transistor performance. Therefore, many researchers are exploring the application of next-generation semiconductor materials, such as transition oxide semiconductors (OSs) and metal dichalcogenides (TMDs), to address these challenges and to realize 3D DRAM. This study provides an overview of the proposed structures for 3D DRAM, compares the characteristics of OSs and TMDs, and discusses the feasibility of employing the OSs and TMDs as the channel material for 3D DRAM. Furthermore, we review recent progress in 3D DRAM using the OSs, discussing their potential to overcome challenges in silicon-based approaches.

High-κ Dielectric (HfO2)/2D Semiconductor (HfSe2) Gate Stack for Low-Power Steep-Switching Computing Devices.

Herein, a high-quality gate stack (native HfO2 formed on 2D HfSe2) fabricated via plasma oxidation is reported, realizing an atomically sharp interface with a suppressed interface trap density (Dit ≈ 5 × 1010 cm-2 eV-1). The chemically converted HfO2 exhibits dielectric constant, κ ≈ 23, resulting in low gate leakage current (≈10-3 A cm-2) at equivalent oxide thickness ≈0.5 nm. Density functional calculations indicate that the atomistic mechanism for achieving a high-quality interface is the possibility of O atoms replacing the Se atoms of the interfacial HfSe2 layer without a substitution energy barrier, allowing layer-by-layer oxidation to proceed. The field-effect-transistor-fabricated HfO2/HfSe2 gate stack demonstrates an almost ideal subthreshold slope (SS) of ≈61 mV dec-1 (over four orders of IDS) at room temperature (300 K), along with a high Ion/Ioff ratio of ≈108 and a small hysteresis of ≈10 mV. Furthermore, by utilizing a device architecture with separately controlled HfO2/HfSe2 gate stack and channel structures, an impact ionization field-effect transistor is fabricated that exhibits n-type steep-switching characteristics with a SS value of 3.43 mV dec-1 at room temperature, overcoming the Boltzmann limit. These results provide a significant step toward the realization of post-Si semiconducting devices for future energy-efficient data-centric computing electronics.

Discovering the anti-cancer phytochemical rutin against breast cancer through the methodical platform based on traditional medicinal knowledge.

A number of therapeutic drugs have been developed from functional chemicals found in plants. Knowledge of plants used for medicinal purposes has historically been transmitted by word of mouth or through literature. The aim of the present study is to provide a systemic platform for the development of lead compounds against breast cancer based on a traditional medical text. To verify our systematic approach, integrating processes consisted of text mining of traditional medical texts, 3-D virtual docking screening, and in vitro and in vivo experimental validations were demonstrated. Our text analysis system identified rutin as a specific phytochemical traditionally used for cancer treatment. 3-D virtual screening predicted that rutin could block EGFR signaling. Thus, we validated significant anticancer effects of rutin against breast cancer cells through blockade of EGFR signaling pathway in vitro. We also demonstrated in vivo anti-cancer effects of rutin using the breast cancer recurrence in vivo models. In summary, our innovative approach might be proper for discovering new phytochemical lead compounds designing for blockade of malignant neoplasm including breast cancer. [BMB Reports 2023; 56(11): 594-599].

Modulation of Contact Resistance of Dual-Gated MoS2 FETs Using Fermi-Level Pinning-Free Antimony Semi-Metal Contacts.

Achieving low contact resistance (RC ) is one of the major challenges in producing 2D FETs for future CMOS technology applications. In this work, the electrical characteristics for semimetal (Sb) and normal metal (Ti) contacted MoS2 devices are systematically analyzed as a function of top and bottom gate-voltages (VTG and VBG ). The semimetal contacts not only significantly reduce RC but also induce a strong dependence of RC on VTG , in sharp contrast to Ti contacts that only modulate RC by varying VBG . The anomalous behavior is attributed to the strongly modulated pseudo-junction resistance (Rjun ) by VTG , resulting from weak Fermi level pinning (FLP) of Sb contacts. In contrast, the resistances under both metallic contacts remain unchanged by VTG as metal screens the electric field from the applied VTG . Technology computer aided design simulations further confirm the contribution of VTG to Rjun , which improves overall RC of Sb-contacted MoS2 devices. Consequently, the Sb contact has a distinctive merit in dual-gated (DG) device structure, as it greatly reduces RC and enables effective gate control by both VBG and VTG . The results offer new insight into the development of DG 2D FETs with enhanced contact properties realized by using semimetals.

Efficient differentiation of human pluripotent stem cells into functional CD34+ progenitor cells by combined modulation of the MEK/ERK and BMP4 signaling pathways.

Differentiation of human pluripotent stem cells (hPSCs) into functional cell types is a crucial step in cell therapy. In the present study, we demonstrate that functional CD34(+) progenitor cells can be efficiently produced from human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs) by combined modulation of 2 signaling pathways. A higher proportion of CD34(+) cells (∼ 20%) could be derived from hPSCs by inhibition of mitogen-activated protein kinase (MAPK) extracellular signal-regulated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling and activation of bone morphogenic protein-4 (BMP4) signaling. hPSC-derived CD34(+) progenitor cells further developed to endothelial and smooth muscle cells with functionality. Moreover, they contributed directly to neovasculogenesis in ischemic mouse hind limbs, thereby resulting in improved blood perfusion and limb salvage. Our results suggest that combined modulation of signaling pathways may be an efficient means of differentiating hPSCs into functional CD34(+) progenitor cells.

Stromal vascular fraction from adipose tissue forms profound vascular network through the dynamic reassembly of blood endothelial cells.

OBJECTIVE: Tremendous efforts have been made to establish effective therapeutic neovascularization using adipose tissue-derived stromal vascular fraction (SVF), but the efficiency is low, and underlying mechanisms and their interaction with the host in a new microenvironment are poorly understood. METHODS AND RESULTS: Here we demonstrate that direct implantation of SVF derived from donor adipose tissue can create a profound vascular network through the disassembly and reassembly of blood endothelial cells at the site of implantation. This neovasculature successfully established connection with recipient blood vessels to form a functionally perfused circuit. Addition of vascular growth factors to the SVF implant improved the efficiency of functional neovasculature formation. In contrast, spheroid culture of SVF before implantation reduced the capacity of vasculature formation, possibly because of cellular alteration. Implanting SVF into the mouse ischemic hindlimb induced the robust formation of a local neovascular network and salvaged the limb. Moreover, the coimplantation of SVF prevented fat absorption in the subcutaneous adipose tissue graft model. CONCLUSIONS: Freshly isolated SVF can effectively induce new vessel formation through the dynamic reassembly of blood endothelial cells and could be applied to achieve therapeutic neovascularization for relieving ischemia and preventing fat absorption in an autologous manner.

[Editing style of Imwon-Gyeongjeji, Inje-ji and inclusion of the medicinal knowledge of the late period of Joseon - Comparing mainly with Dongui-Bogam -].

Imwon-Gyeongjeji which was created by Seo Yu-gu in the first half of the 19th century is a encyclopedia of practical use in rural life. It consists of 113 volumes, 16 fields, and 2.52 million total characters. Of these, the field of medicine comes 11th of the contents covering 28 volumes and 1.1 million characters. Its name is Inje-ji. This paper examines the academic background of Seo Yu-gu and his life work briefly, and investigates the characteristics of medical knowledge of late Joseon period contained in the Imwon-Gyeongjeji, Inje-ji Here, we made key comparisons especially with Dongui-Bogam, Joseon's leading medical book. Of the pioneers of medical history studies of Joseon, a Japanese researcher Miki Sakae has made a negative evaluation to Inje-ji. But after concrete investigation we have come to conclude as follows. First, familial ancestors of Seo Yu-gu were engaged in the introduction of foreign-language books, so Seo Yu-gu as an officer of proof-reading and editing of the various books, also had a lot of knowledge on the medical books ever in history. On this background and experience, for over 36 years from 1,806 retirement from official position to his death, he had compiled and edited Imwon-Gyeongjeji. Second, unlike Dongui-Bogam which included improving health skill, Inje-ji focused on curing medicine readily accessible from the major population of that time. Its main features are as follows: i) prescriptions directly linked to the diseases and symptoms, ii) greatly increased medicinal knowledge especially on infectious diseases and trauma, iii) detailed index easy to look up for prescription and iv) his 'own opinions'[an-seol] which can indicate relevant contents within the book and organically combines the whole knowledge in it. Third, "Inje-ji" utilizing medical books in China and Korea even those of Japan, collected more massively almost all the medical knowledge, new illness, herbs of local area, private prescription. Meanwhile Inje-ji modified the errors of the older medical books like Dongui-Bogam or Bencao-Gangmu, expressed its own subjective views about controversial topics. In summary "Inje-ji" can be the last general medical book which collected and edited almost all the medical knowledge of the period in the East Asia with its own editing format. In addition it is recognized that it pursued an evidence-based medicine and the practical medicine relieving the people, rather than medico-philosophical theories in oriental traditional medicine which was criticized by many critical intellectuals afterwards. Given the scrutiny, it seems that evaluation of the "Inje-ji" by Miki Sakae should be revised by thorough investigations. We are just on the starting line of the Inje-ji research in earnest meaning, and expect this research would give more fruitful and deep perspective in the area of Korea history of medicine.

Device and Circuit Analysis of Double Gate Field Effect Transistor with Mono-Layer WS2-Channel at Sub-2 nm Technology Node.

In this work, WS2 was adopted as a channel material among transition metal dichalcogenides (TMD) materials that have recently been in the spotlight, and the circuit power performance (power consumption, operating frequency) of the monolayer WS2 field-effect transistor with a double gate structure (DG WS2-FET) was analyzed. It was confirmed that the effective capacitance, which is circuit power performance, was greatly changed by the extrinsic capacitance components of DG WS2-FET, and the spacer region length (LSPC) and dielectric constant (KSPC) values of the spacer that could affect the extrinsic capacitance components were analyzed to identify the circuit power performance. As a result, when LSPC is increased by 1.5 nm with the typical spacer material (KSPC = 7.5), increased operating speed (+4.9%) and reduced active power (-6.8%) are expected. In addition, it is expected that the spacer material improvement by developing the low-k spacer from KSPC = 7.5 to KSPC = 2 at typical LSPC = 8 nm can increase the operating speed by 36.8% while maintaining similar active power consumption. Considering back-end-of-line (BEOL), the change in circuit power performance according to wire length was also analyzed. From these results, it can be seen that reducing the capacitance components of the extrinsic region is very important for improving the circuit power performance of the DG WS2-FET.

Optimization of Gate-All-Around Device to Achieve High Performance and Low Power with Low Substrate Leakage.

In this study on multi-nanosheet field-effect transistor (mNS-FET)-one of the gate-all-around FETs (GAAFET) in the 3 nm technology node dimension-3D TCAD (technology computer-aided design) was used to attain optimally reduced substrate leakage from options including a punch-through-stopper (PTS) doping scheme and a bottom oxide (BO) scheme for bottom isolation, with the performance improvement being shown in the circuit-level dynamic operation using the mNS-FET. The PTS doping concentration requires a high value of >5 × 1018 cm-3 to reduce gate induced drain leakage (GIDL), regardless of the presence or absence of the bottom isolation layer. When the bottom isolation is applied together with the PTS doping scheme, the capacitance reduction is larger than the on-state current reduction, as compared to when only the PTS doping concentration is applied. The effects of such transistor characteristics on the performance and capabilities of various circuit types-such as an inverter ring oscillator (RO), a full adder (FA) circuit, and a static random-access memory (SRAM)-were assessed. For the RO, applying BO along with the PTS doping allows the operating speed to be increased by 11.3% at the same power, or alternatively enables 26.4% less power consumption at the same speed. For the FA, power can be reduced by 6.45%, energy delay product (EDP) by 21.4%, and delay by 16.8% at the same standby power when BO and PTS are both applied. Finally, for the SRAM, read current (IREAD) increased by 18.7% and bit-line write margin (BWRM) increased by 12.5% at the same standby power. Through the circuit simulations, the Case 5 model (PTS doping concentration: 5.1 × 1018 cm-3, with BO) is the optimum condition for the best device and circuit performance. These observations confirm that PTS and bottom isolation applications in mNS-FETs can be utilized to enable the superior characteristics of such transistors to translate into high performance integrated circuits.

A steep switching WSe2 impact ionization field-effect transistor.

The Fermi-Dirac distribution of carriers and the drift-diffusion mode of transport represent two fundamental barriers towards the reduction of the subthreshold slope (SS) and the optimization of the energy consumption of field-effect transistors. In this study, we report the realization of steep-slope impact ionization field-effect transistors (I2FETs) based on a gate-controlled homogeneous WSe2 lateral junction. The devices showed average SS down to 2.73 mV/dec over three decades of source-drain current and an on/off ratio of ~106 at room temperature and low bias voltages (<1 V). We determined that the lucky-drift mechanism of carriers is valid in WSe2, allowing our I2FETs to have high impact ionization coefficients and low SS at room temperature. Moreover, we fabricated a logic inverter based on a WSe2 I2FET and a MoS2 FET, exhibiting an inverter gain of 73 and almost ideal noise margin for high- and low-logic states. Our results provide a promising approach for developing functional devices as front runners for energy-efficient electronic device technology.