Current Complementary Metal Oxide Semiconductor Research Articles

Design of a temperature sensor based on a valley photonic crystal Mach–Zehnder interferometer

With the development of photonics device integration technology, Mach–Zehnder interferometers (MZIs) are widely applied as sensors because they are extremely sensitive to environmental parameters. Conventional MZI sensors are generally large and unsuitable for high-density integration. MZIs based on photonic crystals (PCs) can significantly improve compactness and are suitable for integration. However, PC MZIs experience substantial optical loss due to scattering. Based on the spin-valley locking effect that can achieve defect-immune unidirectional transmission of topological edge states in valley photonic crystals (VPCs), we propose an MZI sensor based on a VPC structure and apply it in temperature sensing for what we believe is the first time. The interference peaks redshift with an increase in the temperature, which allows accurate sensing of the temperature shift with a high sensitivity of 0.06 nm/K in the temperature range of 100 K–750 K. The ultracompact device has a small footprint of 9.26×7.99µm2 and a high forward transmittance of 0.88. The design is suitable for the current complementary metal-oxide semiconductor (CMOS) fabrication technique. Thus, it will find broad applications in integrated photonics, optical communication, and integrated temperature sensing.

Area and Device Count Efficient Binary Logic Circuits using Anti‐Ambipolar Switch Devices

AbstractThe unique characteristics of an anti‐ambipolar switch (AAS) device exhibit Λ‐shaped transfer responses (namely delta conductance) and present unique opportunities to overcome the limit of silicon‐based, complementary metal‐oxide‐semiconductor (CMOS) logic circuits. It is crucial because a device that only turns on under a certain bias range can be utilized to simplify the logic circuit and reduce the device count and circuit area required to perform logic functions. In this study, a physically scalable AAS device is investigated using ZnO and dinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene as heterojunction structures to reduce the operating voltage and enhance the peak current and peak‐to‐valley ratio of the AAS device. Moreover, novel logic circuits for AND, OR, XOR, DEMUX, and half‐adder functions are demonstrated using AAS devices. AAS device‐based logic circuits exhibit power‐efficiency characteristics (≈49 times lower than that of the 90‐nm silicon‐based CMOS inverter) and reduce the transistor count and the circuit area by ≈67% and ≈70%, respectively. These results indicate that the use of AAS device‐based logic circuits can be a promising approach to overcome the physical scaling limit of current CMOS technology.

Synthesis and structures of cobalt-expanded zirconium- and cerium-oxo clusters as precursors for mixed-metal oxide thin films.

Transforming current complementary metal-oxide-semiconductor (CMOS) technology to fabricate memory chips and microprocessors into environmentally friendlier electronics requires the development of new approaches to resource- and energy-efficient electron transport and switching materials. Metal and multi-metal oxide layers play a key role in high-end technical applications. However, these layers are commonly produced through high-energy and high-temperature procedures. Herein, we demonstrate our first attempts to obtain stimuli-responsive mixed-metal oxide thin films from solution-processed molecular precursors under milder conditions. The molecular compounds of interest were prepared by one-pot reactions of a CoII carboxylate complex, triethylamine (Et3N), N-butyldiethanolamine (H2bda), and a hexanuclear complex [Ce6O4(OH)4(piv)12] (Hpiv = pivalic acid) or [Zr6O4(OH)4(ib)12(H2O)]·3Hib (Hib = isobutyric acid) in acetonitrile solution. The resulting charge-neutral, heterometallic coordination compounds display a ligand-supported pentanuclear {CeIV3CoIII2} core (in 1) and a dodecanuclear {ZrIV6CoII6} core (in 2), exhibiting thermal stability up to ca. 100 °C in air. Compound 2 was deposited and analyzed on Au(111) and SiO2/Si(100) surfaces to explore its potential as a single-molecule precursor for the preparation of atomically precise, complex mixed-metal oxide thin films. The adsorption characteristics of it demonstrate the ability to form stable agglomerates on the investigated surfaces.

Ferroelectric HfO2: A promising material for next-generation ferroelectric memory devices

Recently, ferroelectric material is playing a more and more important role in the applications of semiconductor devices, especially in random access memory(RAM) devices, and transistors. Compared with traditional flash memories, FRAMs have advantages such as low operation voltage, a huge number of writes, non-volatile properties, and high write speed. However, in the early stage, the main materials used to produce FRAMs are perovskites with crystal structures. Those materials like PbTiO3/PbZr0.3Ti0.7O3 are restricted by the size and the complementary-metal-oxide-semiconductor (CMOS) technology, which is the common technology used to process semiconductor materials. Hafnium oxide material is a newly discovered material with ferroelectricity when doped with Zirconium(Zr). The Hf0.5Zr0.5O2 thin film is an ideal material for FRAMs, which has a smaller size than perovskites FRAMs and is compatible with current CMOS technology, which means lower cost and higher performance. This article aims to explain some properties of hafnium oxide materials based on different aspects, like dopants, thickness, annealing, and electrodes, and elaborate on the advantages of FRAMs made by hafnium oxide materials.

A Simulation-Based Study of Back-Illuminated Lateral Ge/GeSn/Ge Photodetectors on Si Platform for Mid-Infrared Image Sensing

GeSn/Ge heterojunction photodetectors (PDs) have great potential to outperform conventional mid-infrared (MIR) sensors. In this work, simulated analysis is performed to demonstrate the back-illuminated lateral double <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{Ge/}{\text{Ge}}_{\text{0.90}}{\text{Sn}}_{\text{0.10}}\text{/Ge}$</tex-math> </inline-formula> heterojunctions p-i-n PDs for MIR imaging. This lateral PDs configuration is compatible with current complementary metal–oxide–semiconductor (CMOS) technology, yielding reduced fabrication complexity and offering high resonance in optical characteristics (between 2000-and 2700-nm wavelength range), viable for high-performance operation in MIR wavelength bands. This work also investigates the effects of high-density point dislocation at GeSn/Ge heterointerface on various performance metrics, including dark current, photocurrents, detectivity, and noise-equivalent-power (NEP) of PDs. The results indicate that the defects have less impact on detectivity and NEP and have negligible impact on the collection of photogenerated carriers and thus responsivity. The device shows a maximum 3-dB optoelectrical bandwidth of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt;$</tex-math> </inline-formula> 92.4 GHz, which is among the highest of other GeSn p-i-n PDs. In addition, even in the presence of defects, the device achieves high responsivity in MIR bands and its values are 0.39, 1.45, and 0.25 A/W at the operating wavelengths of 2000, 2310, and 2700 nm, respectively. Thus, the proposed work can be a major step toward GeSn-based PDs on the Si platform for MIR imaging applications.

Perspective on Ferroelectric Devices: Lessons from Interfacial Chemistry

Ferroelectric fluorite-structured oxide thin films have attracted increased interest from both academia and industry because of their superior scalability─in which their ferroelectric properties can be maintained even below 10 nm thickness─and excellent compatibility with current complementary metal–oxide–semiconductor technology. Regarding recent efforts to downscale the technology node of semiconductor processing, the emergence of ferroelectric properties in fluorite-structured oxide thin films at small length scales is of particular interest. As the length scale of the fluorite-structured oxide thin films reaches the atomic scale, the contribution of the interfacial layer to the properties naturally increases. In particular, the quality and type of interfacial layer, as well as the reaction chemistry in response to the electric field, play a major role in determining the properties of the devices. Consequently, understanding the chemistry of ferroelectric–electrode and ferroelectric–semiconductor interfaces is crucial for their use in industrial applications in the near future. In this context, emerging semiconductor devices based on fluorite-structured oxide ferroelectrics, including ferroelectric field-effect transistors, ferroelectric random-access memories, and ferroelectric tunnel junctions, and the impact of interface chemistry in the devices are reviewed in detail.

Light Trapping in Conformal CuO/Si Pyramids Heterojunction for Self-Powered Broadband Photodetection

In this letter, we report a conformal CuO/Si micropyramids heterojunction photodetector fabricated by RF reactive magnetron sputtering CuO nanofilm onto the dense and random Si micropyramids. The device presents a prominent photovoltaic effect over the broad wavelength range (300-1300 nm), which enables efficient self-powered broadband photodetection, giving a peak responsivity of 279 mA/W and specific detectivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.18\times10$ </tex-math></inline-formula> 11 Jones at zero bias upon 810 nm illumination at light intensity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.9~\mu \text{W}$ </tex-math></inline-formula> /cm2. Compared to its planar Si counterpart, the conformal CuO/Si pyramids heterojunction photodetector shows a significantly enhanced photoresponse over the broadband region. According to the theoretical simulation of photon absorption in Si pyramid structures, this should be ascribed to the pronounced light trapping effect of the pyramid structures. The light-matter interaction in the heterojunction was accordingly enhanced, leading to the improved photoresponse. This work is well compatible with the current complementary metal-oxide semiconductor (CMOS) technology and provides a facile and effective strategy for the on-chip high performance photodetection.

In-sensor optoelectronic computing using electrostatically doped silicon

Complementary metal–oxide–semiconductor (CMOS) image sensors allow machines to interact with the visual world. In these sensors, image capture in front-end silicon photodiode arrays is separated from back-end image processing. To reduce the energy cost associated with transferring data between the sensing and computing units, in-sensor computing approaches are being developed where images are processed within the photodiode arrays. However, such methods require electrostatically doped photodiodes where photocurrents can be electrically modulated or programmed, and this is challenging in current CMOS image sensors that use chemically doped silicon photodiodes. Here we report in-sensor computing using electrostatically doped silicon photodiodes. We fabricate thousands of dual-gate silicon p–i–n photodiodes, which can be integrated into CMOS image sensors, at the wafer scale. With a 3 × 3 network of the electrostatically doped photodiodes, we demonstrate in-sensor image processing using seven different convolutional filters electrically programmed into the photodiode network. A network of dual-gate silicon p–i–n photodiodes, which are compatible with complementary metal–oxide–semiconductor fabrication processes, can perform in-sensor image processing by being electrically programmed into convolutional filters.

Electromagnetically induced transparency with a single optomechanical microring resonator.

An all-optical realization scheme of electromagnetically induced transparency (EIT) in a single silicon optomechanical microring resonator is proposed and demonstrated. Due to the strong mechanical Kerr effect and well-designed microring resonator, two modes with a resonant frequency separation of 292 GHz (2.35 nm) can be tuned into resonance when the control power is about 4.3 µW, and the EIT spectrum is achieved. Our work provides a constructive solution for realizing EIT in a single microcavity with a low mode density. Furthermore, this device is fully integrated on-chip and compatible with current complementary metal-oxide semiconductor (CMOS) processing and has great potential in applications such as light storage, optical sensing, and quantum optics.

Capacitance matching by optimizing the geometry of a ferroelectric HfO2-based gate for voltage amplification

The voltage amplification of a ferroelectric layer was studied for advanced complementary metal–oxide–semiconductor (CMOS) applications. To match the capacitance for negative-capacitance field-effect transistors (NC-FETs), a method of adjusting the MOS capacitance is proposed by optimizing the width (W) and height/depth (H) in two types of ferroelectric gate-stack 2D metal-oxide semiconductor capacitor (MOSCAP) structures: a fin-like structure and a trench structure. The capacitance of the semiconductor was modeled to match that of the ferroelectric films to obtain hysteresis-free operation (ΔVT = VT, for –VT,rev ~ 0) and achieve voltage amplification (AV). The optimized conditions are found to be H = 19.3 nm and 24.3 nm to achieve the criterion with AV > 50 for the fin-like and trench structure, respectively. Subsequently, the structure was extended to a three-dimensional (3D) fin-shaped field-effect transistor (FinFET) to evaluate the effects of varying geometrical parameters such as the fin spacing (FS). Tuning FS can not only enhance the on-current but also decrease the subthreshold swing in the off-current region. For the FET, the use of the optimum FS value of 30 nm helps the FinFETs achieve capacitance matching with AV > 30. The subthreshold swing of the NC-FinFET is improved by about 47% for HFinFET/WFinFET ~ 3 and Fs/HFinFET ~ 1.2 as compared with the conventional FinFET. The concept of coupling the polarized Hf-based oxide in NC-FETs that is demonstrated to be feasible herein is thus practicable using current CMOS architectures.

Enhanced Light Trapping in Conformal CuO/Si Microholes Array Heterojunction for Self-Powered Broadband Photodetection

In this letter, we demonstrate the fabrication of a conformal CuO/Si microholes array heterojunction through the DC reactive magnetron sputtering from a high-purity Cu target. By using the monolayer graphene as the top electrode, the device served well as a self-powered vis-NIR photodetector, showing a high responsivity of 301.5 mA W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , specific detectivity of 7.96×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> Jones and a fast response speed (rise time 9.9 μ s and fall time 10 μs) upon 530 nm illumination. Compared to its planar counterpart, the responsivity was remarkably enhanced over the broadband region. The underlying reason should be ascribed to the improved light trapping in the microholes via the longitudinal Fabry-Perot (F-P) cavity resonance, according to theoretical simulation by finite-difference time-domain (FDTD) solution. Such an effect gave rise to an enhanced light-matter interaction, leading to the improved photoresponse. This work also opens up an effective way for the on-chip high performance photodetection due to the well compatibility with the current complementary metal-oxide-semiconductor (CMOS) technology.

Robust semiconductor-on-ferroelectric structures with hafnia–zirconia–alumina UTBOX stacks compatible with CMOS technology

Silicon wafers with an ultrathin buried high-k oxide were fabricated by the atomic layer deposition of high-k layers on sapphire and silicon substrates with subsequent silicon layer transfer onto their surfaces by bonding and rapid thermal annealing (RTA). An extremely high thermal stability of hafnia orthorhombic Pca21 ferroelectric phase of up to 1100 °C was observed in the silicon-on-ferroelectric structure on the sapphire substrate. Silicon–ferroelectric–silicon structures with hafnia BOX and alumina inclusions also demonstrated increased thermal stability for hafnia or hafnia–zirconia alloys during the RTA treatment up to 900 °C, which makes them fully compatible with current complementary metal oxide semiconductor technology, promising integrated circuits for neuromorphic computation and optoelectronic switching devices.

Bottom-Gate Approach for All Basic Logic Gates Implementation by a Single-Type IGZO-Based MOS Transistor with Reduced Footprint.

Logic functions are the key backbone in electronic circuits for computing applications. Complementary metal‐oxide‐semiconductor (CMOS) logic gates, with both n‐type and p‐type channel transistors, have been to date the dominant building blocks of logic circuitry as they carry obvious advantages over other technologies. Important physical limits are however starting to arise, as the transistor‐processing technology has begun to meet scaling‐down difficulties. To address this issue, there is the crucial need for a next‐generation electronics era based on new concepts and designs. In this respect, a single‐type channel multigate MOS transistor (SMG‐MOS) is introduced holding the two important aspects of processing adaptability and low static dissipation of CMOS. Furthermore, the SMG‐MOS approach strongly reduces the footprint down to 40% or even less area needed for current CMOS logic function in the same processing technology node. Logic NAND, NOT, AND, NOR, and OR gates, which typically require a large number of CMOS transistors, can be realized by a single SMG‐MOS transistor. Two functional examples of SMG‐MOS are reported here with their analysis based both on simulations and experiments. The results strongly suggest that SMG‐MOS can represent a facile approach to scale down complex integrated circuits, enabling design flexibility and production rates ramp‐up.

PbE (E = S, Se) Colloidal Quantum Dot-Layered 2D Material Hybrid Photodetectors.

Hybrid lead chalcogenide (PbE) (E = S, Se) quantum dot (QD)-layered 2D systems are an emerging class of photodetectors with unique potential to expand the range of current technologies and easily integrate into current complementary metal-oxide-semiconductor (CMOS)-compatible architectures. Herein, we review recent advancements in hybrid PbE QD-layered 2D photodetectors and place them in the context of key findings from studies of charge transport in layered 2D materials and QD films that provide lessons to be applied to the hybrid system. Photodetectors utilizing a range of layered 2D materials including graphene and transition metal dichalcogenides sensitized with PbE QDs in various device architectures are presented. Figures of merit such as responsivity (R) and detectivity (D*) are reviewed for a multitude of devices in order to compare detector performance. Finally, a look to the future considers possible avenues for future device development, including potential new materials and device treatment/fabrication options.

A 1-V, 5 μW, Atto Current Bulk-Driven CMOS Based Operational Transconductance Amplifier for Biosensor Applications

There is an advent need in health industry, for an Implantable Medical Device (IMD) withlower power consumption, noise and area as much as possible, which aims at extending the life-span of the device by enhancing the performance of battery to avoid additional surgery and does not affect the tissue cells. The existing IMD detects a single disorder and consumes high power resulting in need of replacement within a period of time. Furthermore there is a sheer need to reduce the noise factor to achieve an uninterrupted signal. This paper proposes a novel Operational Transconductance Amplifier (OTA) which is used in the biosensors of IMD. The proposed OTA is designed in a 0.18 μm CMOS (Complementary Metal Oxide Semiconductor) technology, the operational frequency is in the range of 0.36 Hz to 50 KHz and capable of measuring the gain in 60 dB. It consumes a negligible amount of (5 μW) power per OTA from 1-V single power supply and achieves minimal input referred noise of 1.24 μVrms, which is highly acceptable for biosensor used in IMD. The post layout simulation of the proposed integrated circuit has been performed successfully.

Test Pattern Generator for MV-Based QCA Combinational Circuit Targeting MMC Fault Models

Quantum-dot-Cellular Automata (QCA) is emerging as one of the alternatives for Integrated Circuit Technology considering the scaling limitations of current Complementary Metal Oxide Semiconductor (CMOS) technology. Being at molecular scale, defects are more likely to occur in QCA devices. Therefore, the substantial development of QCA-oriented defects, its corresponding fault models and test generation is required. This paper addresses the fault model caused by multiple missing cells defect and test generation for these faults for QCA circuits. We have shown that the single missing cell considerations are not enough. Correspondingly, in this paper, testing properties for the detection of fault caused by multiple missing cell defects in QCA devices mainly Majority Voter (MV) are proposed. Even though there are many advanced ATPGs available for CMOS technology, to demonstrate very special MV-based properties with reference to the test pattern generation process and to open the path for advanced combinational and sequential ATPGs specific to MV-based QCA circuits, the extension of basic Automatic Test Pattern Generator is proposed here. The proposed test generation algorithm is guided by the extended Sandia Controllability Observability Analysis Program (SCOAP) testability measures especially for QCA logic primitives.

Mechanical-Resonance-Enhanced Thin-Film Magnetoelectric Heterostructures for Magnetometers, Mechanical Antennas, Tunable RF Inductors, and Filters.

The strong strain-mediated magnetoelectric (ME) coupling found in thin-film ME heterostructures has attracted an ever-increasing interest and enables realization of a great number of integrated multiferroic devices, such as magnetometers, mechanical antennas, RF tunable inductors and filters. This paper first reviews the thin-film characterization techniques for both piezoelectric and magnetostrictive thin films, which are crucial in determining the strength of the ME coupling. After that, the most recent progress on various integrated multiferroic devices based on thin-film ME heterostructures are presented. In particular, rapid development of thin-film ME magnetometers has been seen over the past few years. These ultra-sensitive magnetometers exhibit extremely low limit of detection (sub-pT/Hz1/2) for low-frequency AC magnetic fields, making them potential candidates for applications of medical diagnostics. Other devices reviewed in this paper include acoustically actuated nanomechanical ME antennas with miniaturized size by 1–2 orders compared to the conventional antenna; integrated RF tunable inductors with a wide operation frequency range; integrated RF tunable bandpass filter with dual H- and E-field tunability. All these integrated multiferroic devices are compact, lightweight, power-efficient, and potentially integrable with current complementary metal oxide semiconductor (CMOS) technology, showing great promise for applications in future biomedical, wireless communication, and reconfigurable electronic systems.

Water-Based Solution Processing and Wafer-Scale Integration of All-Graphene Humidity Sensors.

One of the main advantages of 2D materials for various applications is that they can be prepared in form of water‐based solutions. The high yield and cost‐effectiveness of this method make them of great interest for printed electronics, composites, and bio‐ and healthcare technologies. However, once deposited on a substrate, etching away these solution‐processed materials is a difficult task, yet crucial for pattern definition and thus device fabrication. In particular, the realization of micrometer‐sized patterns requires mesh and paste optimization when screen‐printed or solvent‐engineered and surface functionalization when inkjet‐printed, both usually involving additional postdeposition steps. These constraints are holding back the integration of these 2D materials in devices and applications. In this work, a method for the fabrication of micrometer‐sized well‐defined patterns in water‐based 2D materials is presented, with an extensive characterization of the films and patterns obtained. The method is ultimately used to create humidity sensors with performance comparable to that of commercial ones. These sensor devices are fabricated onto a 4′ silicon and polyethylene terephthalate (PET) wafers to create all‐graphene humidity sensors that are flexible, transparent, and compatible with current complementary metal–oxide–semiconductor (CMOS) and roll‐to‐roll workflows.

Surface, phase transition and impedance studies of Zr- mutated BaTiO3 lead-free thin films

Abstract Lead (Pb) based electronic materials are facing global restriction due to the toxicity of lead. Presently, there is a need for designing and studying Pb-free thin films. In the present work, we fabricated lead-free Zr-substituted BaZr0.1Ti0.9O3 (BZT10) and BaZr0.2Ti0.8O3 (BZT20) thin films on Pt/TiO2/SiO2/Si substrates by sol-gel method using spin coating technique. The major drawback of BZT solid solutions is high processing temperature (1400 °C−1500 °C). For fabrication of micro-system devices compatible with the current complementary metal oxide semiconductor (CMOS) technology, the primary requirement is fabrication of BZT thin films at lower processing temperature. So, we have developed BZT thin films at low annealing temperature 750 °C. The prepared thin films were characterized by grazing incidence X-ray diffraction (GIXRD) and Raman spectroscopy for structural study. The phase variation from tetragonal to cubic with Zr concentration has been noticed in the structural analysis and is consistent with temperature dependent dielectric study. Surface studies of thin film are related to the functionality of thin film in various technical applications. The average grain size and root mean square (RMS) roughness were calculated from Atomic Force Microscope (AFM) images. Local elastic properties have been analyzed by force modulation mode of AFM. The ferroelectric properties of BZT thin films decrease on increasing Zr content to 20 mol%. Impedance spectroscopy analysis at different bias voltages has been carried out for these lead-free BZT thin films. The high value of dielectric constant and impedance makes BZT worthy material for many technical applications.

Transient Negative Capacitance Effect in Atomic‐Layer‐Deposited Al2O3/Hf0.3Zr0.7O2 Bilayer Thin Film

AbstractThe negative capacitance (NC) effect is now attracting a great deal of attention in work towards low‐power operation of field effect transistors and extremely large capacitance density in dynamic random access memory. However, to date, observation of the NC effect in dielectric/ferroelectric bilayer capacitors has been limited to the use of epitaxial ferroelectric thin films based on perovskite crystal structures, such as Pb(Zr,Ti)O3 and BaTiO3, which is not compatible with current complementary metal oxide semiconductor technology. This work, therefore, reports on the transient NC effect in amorphous‐Al2O3/polycrystalline‐Hf0.3Zr0.7O2 bilayer systems prepared using atomic layer deposition. The thin film processing conditions are carefully tuned to achieve the appropriate ferroelectric performances that are a prerequisite for the examination of the transient NC effect. Capacitance enhancement is observed in a wide voltage range in 5–10 nm thick Al2O3/Hf0.3Zr0.7O2 bilayer thin films. It is found that the capacitance of the dielectric layer plays a critical role in the determination of additional charge density induced by the NC effect. In addition, inhibition of the leakage current is important for stabilization of nonhysteretic charge–discharge behavior of the bilayers. The mean‐field approximation combined with classical Landau formalism precisely reproduces the experimental results.