1,720,975 research outputs found
Study on Charge-Enhanced Ferroelectric SIS Optical Phase Shifters Utilizing Negative Capacitance Effect
No full textSi optical phase shifters are key components for efficient phase modulation utilizing carrier modulation. Among many structures for carrier modulation in them, a semiconductor-insulator-semiconductor (SIS) capacitor can achieve high phase modulation efficiency because of its large carrier accumulation. However, due to the limitation caused by relatively small plasma dispersion in Si, its size and voltage for the pi phase shift are large to integrate into conventional CMOS technology. To enhance its phase modulation efficiency, material engineering of a SIS capacitor is indispensable. Although semiconductor engineering has been proved to realize efficient phase modulation, there are few reports on the insulator engineering of a SIS capacitor for efficient phase modulation. Therefore, we have introduced new functionalities for a SIS optical phase shifter using insulator engineering. In this paper, we have investigated the charge enhancement effect in a SIS capacitor with ferroelectric (FE) materials utilized by the negative capacitance (NC) effect. We will discuss the design of an NC SIS optical phase modulator to enhance this effect for a new efficient phase modulation scheme.
Proposal of P-Channel FE NAND with High Drain Current and Feasible Disturbance for Next Generation 3D NAND
No full textRecently the demand for higher drain current and scalable gate stack thickness arises for next-generation 3D NAND flash, due to the physical limit of cells and stacked layers over 1,000. While the N-channel ferroelectric field-effect-transistor (n-FEFET) has been studied to overcome the limit, it brings the critical reliability issue due to parasitic electron trapping during the program and read, which degrades retention, endurance and induces disturbance and cell failure. We show the feasibility of 2-bit multi-level-cell (MLC) p-channel FEFET (p-FEFET) for (embedded) NAND flash memory application. P-FEFET intrinsically has higher on-current than n-FEFET. It is due to the absence of hole trapping, which leads to ferroelectric charge boosting at the channel. Other properties (retention, disturbance, etc) also show that p-FEFET has remarkably improved electrical characteristics when it is targeted for NAND flash, rather than nFEFET. Finally, we propose a strategy for engineering the pFENAND device
Strategy for 3D Ferroelectric Transistor: Critical Surface Orientation Dependence of HfZrOx on Si
No full textSi surface orientation is one of the crucial factors to determine the performance of 3D-structured devices such as fin-, nanosheet-and vertical-field-effect transistors. We reveal that the crystallization annealing temperature, remnant polarization (Pr), and coercive field (Ec) of the ferroelectric HfZrOx stack on Si show strong surface orientation dependence. We evaluate HfZrOx - based FEFET on Si with different orientations for both memory and logic applications. Based on the findings, the impact of surface orientation in SOI FE FinFET is shown. Finally, we suggest a strategy for 3Dstructured FEFET with targeted applications
Epitaxial Lift-Off Technology for Large Size III-V-on-Insulator Substrate
No full textIII-V materials can be a very good channel candidate for monolithic 3D (M3D) integration due to the potential of high-performance and lower process temperature as compared with Si, since a low process temperature is crucial to avoid degradation of bottom devices. For III-V M3D integration, material transfer techniques are important, and such processes should be enabled by low process costs on a large wafer scale. In this study, we propose an InGaAs channel transfer technique by wafer bonding, epitaxial lift-off and III-V layers grown on Si substrate. Effective mobility of fabricated MOS HEMTs using transferred InGaAs layer was 1.3 times higher than that of Si MOSFETs. The proposing channel transfer technique would be useful for M3D integration because it provides wafer scalability, cost-effectiveness, back-gate biasing, and etc.
Logic and Memory Ferroelectric Field-Effect-Transistor Using Reversible and Irreversible Domain Wall Polarization
No full textWe propose a higher-κ non-hysteric ferroelectric field-effect transistor (FEFET) using reversible domain wall displacement. By separately stimulating reversible and irreversible domain walls, whose concepts have been experimentally suggested recently, our HfZrOx-based FEFET showed remarkable performance as both a logic and a memory device. This was achieved by relatively low-temperature annealing, contributing to the formation of more reversible domain walls in the film. Finally, we demonstrated the feasibility of logic and memory co-integration by common fabrication process with complementary metal-oxide-semiconductor (CMOS) compatibility.
Proposal of Block Erase and Verify Schemes for Ferroelectric NAND: Overcoming Critical Challenges from Threshold Voltage Polarity
No full textSuperior QLC Retention Enhancement of a Large Memory Window FEFET Through Gate Stack Engineering
No full text3-D NAND flash cells with ferroelectric field-effect transistors (FEFETs) have gained significant attention due to emerging challenges in 3-D NAND technology. Although metal-insulator-ferroelectric-insulator-semiconductor (MIFIS) structures provide large memory windows (MWs), FEFET is still under extensive research and faces critical issues such as data retention, write endurance, disturbance, variability, scalability, gate stack thickness, write voltage, and thermal stability of FE-HfO2. Here, we propose a novel gate stack, metal-insulator-high k insulator-ferroelectric-insulator-semiconductor (MIKFIS) to address these challenges. The MIKFIS FEFET achieves a large MW of 12.2 V and demonstrates highly enhanced quad-level-cell (QLC) data retention at both 24 C-degrees and 85 C-degrees. Moreover, MIKFIS offers additional benefits, including reduced monoclinic-(m-) phase formation, reduced gate stack thickness, decreased equivalent oxide thickness (EOT), and enhanced FE switching. The origin of the superior retention of MIKFIS is investigated using a revised measurement technique developed to accurately extract polarization.
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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