Device Dimensions Research Articles

An H-Plane Groove Gap Waveguide Magic-T for X-Band Applications

An X-band H-plane groove gap waveguide magic-T is presented as a combination of an H-plane and an E-plane T-junction. Two architectures can be derived by orientating the sum and difference ports to the same or opposite directions, respectively. Slot coupling allows the reduction of the device dimensions along the E-plane, and such a low profile can be attractive in all groove gap waveguide applications where compactness is required. A proof-of-concept prototype is fabricated with standard low-cost CNC milling machine manufacturing techniques. Good agreement between simulations and measurements is observed.

A detailed investigation of dielectric-modulated dual-gate TMD FET based label-free biosensor via analytical modelling

In this work, an analytical model is developed for DM-DG-TMD-FET- based Biosensor including Fringing-field effects. The Analytical model has been developed for two different Device structures, namely Device structure-1 (without a gate above the nano-cavity) and Device structure-2 (with a gate above the nano-cavity) based on modulation of the dielectric constant of biomolecules in the nano-cavity region. The proposed model has been validated against both numerical quantum simulation results with the help of a few fitting parameters and it also agrees with the 2-dimensional numeric simulator SILVACO TCAD used in this work. The presence/absence of biomolecules has been detected by the metric of threshold voltage sensitivity S_{Vth} and drain current I_{d} for the neutral as well as charged biomolecules. Sensitivities of partially filled nano-cavities arising out of steric hindrance in both the biosensors are compared. Optimization of device dimensions has also been included in this work to enhance the sensitivity of the biosensors. It has been witnessed that the sensitivity of the proposed biosensor is sim 100% higher in Device structure-1 for neutral biomolecules with dielectric constant kappa = 12, when compared to Device structure-2 for fully filled cavities. Whereas for the charged biomolecules, Device structure-1 shows sim 50% enhanced sensitivity than Device structure-2 for N_{f}=-1times 10^{-12}text{C}/text{cm}^2. Device structure-1 demonstrates sim120% higher sensitivity than Device structure-2 with partially filled cavities (i.e. 66% filled cavity). Finally, benchmarking of the proposed biosensor is presented with contemporary, state-of-the-art biosensors and it is highlighted that MoS_{2} FET-based biosensor emerges with a superior sensitivity of S_{Vth} = 0.81 V for kappa = 12.

Journey of MOSFET from Planar to Gate All Around: A Review.

With the continuous miniaturization in device dimension to reach the expectation raised by semiconductor users, the shape and size of the MOSFET are changing periodically. The journey started in the year 1960, reached the milestone, and still going on to create history. Due to continuous downscaling, the device dimensions have already reached the critical limit and further miniaturization is a challenge. As a result of which some unwanted effects were raised unknowingly to suppress the device performances while entering into nanoscale. To overcome these kinds of barriers, different device architectures were proposed to keep the journey on. This paper focused on those types of advanced structures in MOSFET, which kept Moore's law alive.

FEops HEARTguide Patient-Specific Computational Simulations for WATCHMAN FLX Left Atrial Appendage Closure: A Retrospective Study

BackgroundThree-dimensional transesophageal echocardiography (3D-TEE) is the primary imaging tool for left atrial appendage closure planning. The utility of cardiac computed tomography angiography (CCTA) and patient-specific computational models is unknown. ObjectivesThe purpose of this study was to evaluate the accuracy of the FEops HEARTguide patient-specific computational modeling in predicting appropriate device size, location, and compression of the WATCHMAN FLX compared to intraprocedural 3D-TEE. MethodsPatients with both preprocedural and postprocedural CCTA and 3D-TEE imaging of the LAA who received a WATCHMAN FLX left atrial appendage closure device were studied (n = 22). The FEops HEARTguide platform used baseline CCTA imaging to generate a prediction of device size(s), device position(s), and device dimensions. Blinded (without knowledge of implanted device size/position) and unblinded (implant device size/position disclosed) simulations were evaluated. ResultsIn 16 (72.7%) patients, the blind simulation predicted the final implanted device size. In these patients, the 3D-TEE measurements were not significantly different and had excellent correlation (Pearson correlation coefficient (r) ≥ 0.90). No patients had peridevice leak after device implant. In the 6 patients for whom the model did not predict the implanted device size, a larger device size was ultimately implanted as per operator preference. The model measurements of the unblinded patients demonstrated excellent correlation with 3D-TEE. ConclusionsThis is the first study to demonstrate that the FEops HEARTguide model accurately predicts WATCHMAN FLX device implantation characteristics. Future studies are needed to evaluate if computational modeling can improve confidence in sizing, positioning, and compression of the device without compromising technical success.

A capillary flow-driven microfluidic device for point-of-care blood plasma separation

Plasma has significant utility as an input for diagnostics and screening for conditions such as viral infections, cancer, and more. However, plasma is difficult to obtain at the point-of-care, as separation from whole blood is typically carried out via centrifugation. We have designed and optimized a low-cost, simple-to-operate microfluidic device which carries out the separation of plasma from whole blood. The device utilizes depth filtration as its separation mechanism and collects plasma via capillary action, allowing for operation without components that drive flow externally. We first optimized device dimensions and operating parameters and demonstrated consistent separation efficiencies for the samples with hematocrits ranging from 25–65%. The impact of input sample hematocrit percentage on flow rate through the device was also examined, with samples with hematocrits greater than 45% decreasing plasma flow rate. Lastly, we evaluated the ability of this device to produce plasma with a high protein concentration and found no significant difference between protein levels in samples from the device compared to samples produced via centrifugation. This system produced plasma with a maximum separation efficiency of 88.5% and achieved a maximum plasma volume of ∼14 μl from a 50 μl whole blood input. The low cost, simplicity of operation, and high plasma quality associated with this device give it many advantages in a point-of-care setting. This device could be integrated into plasma-based diagnostic workflows to increase access to various types of disease testing and monitoring.

Atomic layer deposition of conductive and semiconductive oxides

Conductive and semiconductive oxides constitute a class of materials of which the electrical conductivity and optical transparency can be modulated through material design (e.g., doping and alloying) and external influences (e.g., gating in a transistor or gas exposure in a gas sensor). These (semi)conductive oxides, often categorized as amorphous oxide semiconductors or transparent conductive oxides, have, therefore, been commonplace in, for example, solar cells and displays, as well as in an increasing variety of other applications including memory, logic, photonics, and sensing. Among the various deposition techniques, the use of atomic layer deposition (ALD) has been gaining in popularity in recent years. Specifically since the early 2000s, many ALD processes for doped and compound conductive metal oxides have been developed. The interest in such oxides prepared by ALD can most likely be attributed to the distinct merits of ALD, such as low-temperature processing, excellent uniformity and conformality, and accurate control over the doping level and composition. Moreover, as device dimensions shrink the need for high-quality, ultrathin materials becomes ever more important. These merits of ALD stem directly from the self-limiting nature of the surface chemistry that drives the ALD growth. On the other hand, the strong role that surface chemistry has in the growth mechanism brings in many intricacies, and detailed understanding of these aspects has been vital for the development of high-quality doped and compound oxides by ALD. Examples of growth effects that can occur during ALD of compound oxides include growth delays, clustering of dopants, and interruption of grain growth by doping. Such effects often need to be accounted for or mitigated, while on the other hand, there are also clear cases where such growth effects can be leveraged to achieve enhanced or new functionality. In this review paper, an overview of the library of ALD processes that has emerged is presented. Available precursor chemistries, dopants as well as achieved film properties—most notably the carrier densities and (field-effect) mobilities of the films—are presented. A selection of important ALD effects that can occur during the deposition of doped and compound conductive oxides is showcased, and their effect on the optical and electrical properties are highlighted. Mitigation and improvement strategies for negative growth effects are presented. This is done through case studies that clearly illustrate these effects, drawing both from literature and from our own recent work.

Operation Mechanisms of Flexible RF Silicon Thin Film Transistor under Bending Conditions

We fabricate a flexible silicon thin-film transistor (TFT) on a plastic substrate as a key component and representative example to analyze the major influencing factors of flexible devices under bending conditions. Experimental and two-dimensional device modeling results reveal that bending radius and device dimensions have a significant influence on the radio-frequency (RF) performance of the flexible silicon nanomembrane (SiNM) TFT under bending conditions. Carrier mobility and electric field extracted from the model, together with theoretical analysis, were employed to study the performance dependence and the operation mechanisms of the bended TFTs. The carrier mobility and electric field are increased monotonically with larger bending strains, which lead to better RF performance. They also showed a consistent change trend with different device parameters (e.g., gate length, oxide thickness). Flexible SiNM TFTs with a smaller gate length and a larger gate dielectric thickness are shown to have better RF performance robustness with bending strains. The analysis provides a guideline for the study of flexible electronics under bending conditions.

Certification of Genuine Multipartite Entanglement with General and Robust Device-Independent Witnesses.

Genuine multipartite entanglement represents the strongest type of entanglement, which is an essential resource for quantum information processing. Standard methods to detect genuine multipartite entanglement, e.g., entanglement witnesses, state tomography, or quantum state verification, require full knowledge of the Hilbert space dimension and precise calibration of measurement devices, which are usually difficult to acquire in an experiment. The most radical way to overcome these problems is to detect entanglement solely based on the Bell-like correlations of measurement outcomes collected in the experiment, namely, device independently. However, it is difficult to certify genuine entanglement of practical multipartite states in this way, and even more difficult to quantify it, due to the difficulty in identifying optimal multipartite Bell inequalities and protocols tolerant to state impurity. In this Letter, we explore a general and robust device-independent method that can be applied to various realistic multipartite quantum states in arbitrary finite dimension, while merely relying on bipartite Bell inequalities. Our method allows us both to certify the presence of genuine multipartite entanglement and to quantify it. Several important classes of entangled states are tested with this method, leading to the detection of genuinely entangled states. We also certify genuine multipartite entanglement in weakly entangled Greenberger-Horne-Zeilinger states, showing that the method applies equally well to less standard states.

Threshold Voltage Control in Dual‐Gate Organic Electrochemical Transistors

AbstractOrganic electrochemical transistors (OECTs) based on Poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) are a benchmark system in organic bioelectronics. In particular, the superior mechanical properties and the ionic‐electronic transduction yield excellent potential for the field of implantable or wearable sensing technology. However, depletion‐mode operation PEDOT:PSS‐based OECTs cause high static power dissipation in electronic circuits, limiting their application in electronic systems. Hence, having control over the threshold voltage is of utmost technological importance. Here, PEDOT:PSS‐based dual‐gate OECTs with solid‐state electrolyte where the threshold voltage is seamlessly adjustable during operation are demonstrated. It is shown that the degree of threshold voltage tuning linearly depends on the gate capacitance, which is a straightforward approach for circuit designers to adjust the threshold voltage only by the device dimensions. The PEDOT:PSS‐based dual‐gate OECTs show excellent device performance and can be pushed to accumulation‐mode operation, resulting in a simplified and relaxed design of complementary inverters.

STUDY OF CHANGES IN HYDRODYNAMIC PARAMETERS PATTERNS OF VISCOUS FLUID FLOW IN A FLAT DIFFUSER

The relevance. Diffusers, either as nozzles or constituent elements, are frequently used in many mechanisms and machines. In this regard, the study of viscous fluid flow in diffusers aims to discover patterns of changes in the flow's hydrodynamic parameters, allowing better understanding of the nature of flow as a function of Reynolds number. Following the results of the analysis of the study, conditions for the proper construction of the mechanism unit, ensuring its reliable and durable operation will be revealed. The main aim of this study is to determine the velocity profiles in the flat diffuser for a viscous incompressible fluid by integrating the simplified Navier–Stokes differential equations under the established initial and boundary conditions, as well as the bifurcation point's dependence on the opening angle and Reynolds number of the diffuser. Objects: a flat diffuser in which viscous incompressible fluid moves. At the same time, revealing the patterns of changes of the hydrodynamic parameters of the flow is of defining value when choosing the structural dimension of devices and mechanisms, the main part of which is the flat diffuser. Methods. To reveal the patterns of changes of the hydrodynamic parameters of the flow in a flat diffuser, the study is based on the fundamental nonlinear differential equations of viscous fluid mechanics, which in a general case are not subject to an exact mathematical solution. For integration in the nonlinear differential equations, due to the smallness, the nonlinear-convective terms are neglected, and the inertial terms are also partially simplified. Such a simplification is justified if the velocities are very small or if the dynamic coefficient of viscosity of the fluid is very large. A method for solving the boundary value problem was developed, and regularities for changing the flow parameters were obtained. According to the derived regularities, graphs of the change in velocity, pressure and shear stresses on the wall of the fixed channel were plotted and the coordinates of the separation point were determined. Results. Depending on the angle of the diffuser opening and the Reynolds number, a general solution of the approximating Navier–Stokes equations was given. In accordance with the nature of the motion, the boundary conditions of the problem were established and the boundary value problem was stated. A method for integrating a boundary value problem was developed, and regularities for the change in velocities along the length of the diffuser were obtained for a parabolic distribution of velocities in the inlet sections. Graphs of the change in radial velocities along the length and at a fixed value of the opening angle were constructed, a flow pattern and the transition of a single-mode flow to multimode operation were obtained. For a fixed opening angle and Reynolds number, the conditions for flow separation from a fixed wall were derived, where the flow velocity changes the sign.

A Normalized Model of a Microelectromechanical Relay Calibrated by Laser-Doppler Vibrometry.

This work presents a behavioral model for a microelectromechanical (MEM) relay for use in circuit simulation. Models require calibration, and other published relay models require over a dozen parameters for calibration, many of which are difficult to extract or are only available after finite element analysis. This model improves on prior work by taking advantage of model normalization, which often results in models that require fewer parameters than un-normalized models. This model only needs three parameters extracted from experiment and one dimension known from device fabrication to represent its non-contact behavior, and two additional extracted parameters to represent its behavior when in contact. The extracted parameters–quality factor, resonant frequency, and the pull-in voltage–can be found using laser Doppler vibrometry. The device dimension is the actuation gap size, which comes from process data. To demonstrate this extraction process, a series of velocity step responses were excited in MEM relays, the measured velocity responses were used to calibrate the model, and then then simulations of the model (implemented in Verilog-A) were compared against the measured data. The error in the simulated oscillation frequency and peak velocity, two values selected as figures of merit, is less than 10% across many operating voltages.

(Invited) Addressing Key Process and Material Challenges to Enable 2D Transition Metal Dichalcogenide Channels in Advanced Logic Devices

Two dimensional ultrathin layers are considered promising materials to bring new functionalities in nanotechnologies and candidate to replace 3D materials in existing applications. Among this last category, transition metal dichalcogenides (TMDC) like WS2, MoS2, WSe2 are viewed as interesting alternative channels for ultra-scaled CMOS technologies, as silicon is approaching its physical limits. These semiconductor 2D monolayers could bring a decisive advantage in terms of electrostatic control at very low gate length, while maintaining decent carrier transport properties as compared to 3D materials at same dimension. In addition, TMDC should provide improved off current performance as compared to silicon, an important factor to improve the static power efficiency in multibillion transistor chips. Obviously, replacing the channel material of the main device in microelectronics, from silicon to TMDC, comes with a very long list of scientific and technological challenges to be addressed. In this paper we limit our scope to the growth of TMDC, one of the main pillar in this global effort, and share how we addressed some of the challenges related to the formation of 2D semiconductor channels, to enable the fabrication of functioning devices on lab and 300 mm flows.TMDCs thin films grown with metal oxide CVD on substrates with, in some case, the presence of NaCl salts, are demonstrating the largest grain size and the best electrical performance but these processes are hardly compatible with industrial CVD reactors. In contrast we use chemistries more compatible with manufacturing, with the target of growing TMDC on 300 mm substrates. We report on MoS2 and WS2 formed with chemistries using metal organic precursors such as Mo(CO)6 or W(CO)6 and di-hydrogen sulfide grown in customized epitaxial cross flow 200 and 300 mm reactors [1]. We report basic nucleation and growth studies over a large process domain which show the possibility to control the density of nuclei and the subsequent lateral crystal growth while minimizing secondary nucleation and metal particle defectivity.We study the deposition of MoS2 an WS2 on two basic types of substrates defining fundamentally the integration schemes. On one route, dedicated to device performance demonstration, TMDC monolayers are grown on templated substrates like sapphire following a van der Waals epitaxy mode which enables regular orientation of the crystallites and formation of large and oriented domains after grain ripening with reduced defect concentration. The 2D layer is then transferred onto the final substrate for the device formation. With this technique, average mobilities above 30 cm2/Vs have been achieved regularly on MoS2 backgated devices, and the best devices exhibit currents at transfer curve up to 420 mA/mm [2,3]. On the other flow, recent efforts have aimed at growing WS2 directly on various types of amorphous substrate layer typically deposited on 300mm wafer, acting either as bottom gate dielectric or sacrificial layer. This scheme doesn’t require subsequent transfer step. However, after integration, these materials demonstrate performance still substantially lower than with material grown on sapphire [4,5].As the device dimensions has scaled down over the last 20 years, improving the variability at different scales has emerged as major topic in microelectronics. TMDC channels are no exception to this trend despite intrinsic advantage in terms of thickness control. We will share on specific work done on sapphire surface specification and preparation. We have demonstrated that depositing MoS2 on 1° off-A axis C-plane sapphire substrate reduced the dispersion in mobility as compared to similar materials obtained on C-plane oriented on-axis substrates [6]. We have also worked-out in-situ Cl2 etch process to remove the superficial islands grown on top of the first layer MoS2 crystals as this first layer is being closed. The process enables full lateral etching of the secondary layer crystals selectively to the closed first layer. With this process, we observed substantial improvement in the electrostatic control of MoS2 scaled transistors, including threshold voltage variability and improved subthreshold swing control [7].We continue to work out the TMDC growth process to improve the material quality, impacted by the presence of defects at the grain boundaries or intra-grain, aiming to close the gap with advanced logic requirements.1-Caymax & al., SSDM, D-1-03, 20192-D Lin & al., Symposium on VLSI Technology, 1-2, 20213- Wu & al., IEDM, 7.4.1-7.4.4, 20214- Asselberghs & al., IEDM, 40.2.1- 40.2.4, 20205- Smets & al., IEDM, 34.2.1-34.2.4, 20216- Shi & al., ACS nano 15 (6), 9482-9494, 20217- Shi & al., IEDM, 37.1.1-37.1.4, 2021

(Invited) Nm-Scale Patterns and Selectivity: A Blessing or a Curse

Area-selective deposition (ASD) is a promising technique for semiconductor device manufacturing. The replication of nanoscale patterns by ASD can simplify device fabrication process flows by reducing the number of lithography, etch and chemical-mechanical polishing steps. In addition, ASD could eliminate pattern overlay errors. ASD is of special interest as device dimensions scale and has recently been shown as viable approach for the fully self-aligned via, to enable interconnect scaling beyond the 3 nm node [1]. However, the dependence of the selectivity of ALD and CVD processes on the patterning process and pattern dimensions is poorly documented. This aspect will be investigated in the current presentation. We will discuss the fundamental mechanisms of ALD growth mechanisms and how they influence selectivity. Next, we will discuss an example of Ru ASD with defect mitigation in nm-scale patterns on full 300-mm wafers [2].[1] Chen et al., IEDM21, 486-489.[2] Clerix et al., Adv. Mater. Interfaces 2021, 2100846.

Process Development of Amorphous Indium Tin Gallium Oxide (ITGO) Thin Film Transistors

The invention of portable electronic devices had a huge impact on the growing interest in flat panel displays. Since the first report in 2004 on amorphous Indium Gallium Zinc Oxide (a-IGZO) thin film transistors (TFTs), many companies have become interested in this material. The main advantage of a-IGZO over conventional amorphous silicon TFTs is its steep subthreshold, low off state current, and high channel mobility. However, the demand for larger displays with higher resolution and refresh rates is driving the demand for TFTs with higher performance, while avoiding the cost and complexity associated with low temperature polycrystalline silicon. There is an increased focus on alternative amorphous oxide semiconductors for use as TFT channel materials, due to the success of a-IGZO.The focus of this study is an investigation on Indium-Tin-Gallium-Oxide (ITGO) TFTs. Unpassivated bottom-gate devices were fabricated with a 30nm a-ITGO film, sputter deposited with 1% and 10% oxygen gas ambient, followed by a 2 hour anneal at 300oC in oxygen. Devices fabricated with PO2 = 1% resulted in a highly conductive channel. Devices with PO2 = 10% displayed semiconducting behavior and a shallow subthreshold. This trend held for all device dimensions tested; lengths of 24µm, 12µm, and 6µm with a width of 24µm. Compared to a-IGZO devices with a length of 4µm, ITGO devices with a length of 12µm exhibit an equivalent current drive, implying a 3 to 4 times improvement in mobility.Following aging in room ambient for multiple days, a-ITGO devices displayed improved yet left-shifted transfer characteristics. In unpassivated a-IGZO devices, similar behavior can also be observed and is attributed to an inhomogeneous trap distribution across the channel. As the exposed channel reacts with room air, oxygen vacancies are filled resulting in a more homogeneous trap distribution. A radial variation of device performance from the center of the wafer to the edge was also observed. When measuring devices towards the edge of the wafer a considerable left shift in transfer characteristics was observed. This variation in device performance is believed to be attributed to non-uniformities in the as deposited ITGO film and will be related to material optical parameters. Figure 1

Powering Solutions for Biomedical Sensors and Implants Inside the Human Body: A Comprehensive Review on Energy Harvesting Units, Energy Storage, and Wireless Power Transfer Techniques

For implantable medical devices, it is of paramount importance to ensure uninterrupted energy supply to different circuits and subcircuits. Instead of relying on battery stored energy, harvesting energy from the human body and any external environmental sources surrounding the human body ensures prolonged life of the implantable devices and comfort of the patients. In this article, we present existing issues and challenges related to the state-of-the-art solutions used for harvesting energy to power implantable devices. In addition, the details on existing energy storage technologies and various wireless power transfer techniques incorporating external or internal energy sources and sensors have been discussed. The authors have outlined the performance and power constraints of existing biomedical devices and provided a brief overview of various power architectures found in the literature. This survey has been conducted on existing implantable solutions in terms of output voltage, current, device dimension, application, generated power, energy density, and so on. Finally, the advantages and drawbacks of different solutions have been discussed and compared. Therefore, this article can be considered as an expedient reference for researchers conducting research in the field of energy scavenging, internal energy storage, wireless power transfer techniques, and power management of implantable medical devices.

How precise is PreSize Neurovascular? Accuracy evaluation of flow diverter deployed-length prediction.

The use of flow-diverting stents has been increasingly important in intracranial aneurysm treatment. However, accurate sizing and landing zone prediction remain challenging. Inaccurate sizing can lead to suboptimal deployment, device waste, and complications. This study presents stent deployment length predictions offered in medical software (PreSize Neurovascular) that provides physicians with real-time planning support, allowing them to preoperatively "test" different devices in the patient's anatomy in a safe virtual environment. This study reports the software evaluation methodology and accuracy results when applied to real-world data from a wide range of cases and sources as a necessary step in demonstrating its reliability, prior to impact assessment in prospective clinical practice. Imaging data from 138 consecutive stent cases using the Pipeline embolization device were collected from 5 interventional radiology centers in the United Kingdom and retrospectively analyzed. Prediction accuracy was calculated as the degree of agreement between stent deployed length measured intraoperatively and simulated in the software. The software predicted the deployed stent length with a mean accuracy of 95.61% (95% confidence interval [CI] 94.87%-96.35%), the highest reported accuracy in clinical stent simulations to date. By discounting 4 outlier cases, in which events such as interactions with coils and severe push/pull maneuvers impacted deployed length to an extent the software was not able to simulate or predict, the mean accuracy further increases to 96.13% (95% CI 95.58%-96.69%). A wide discrepancy was observed between labeled and measured deployed stent length, in some cases by more than double, with no demonstrable correlation between device dimensions and deployment elongation. These findings illustrate the complexity of stent behavior and need for simulation-assisted sizing for optimal surgical planning. The software predicts the deployed stent length with excellent accuracy and could provide physicians with real-time accurate device selection support.

An FDTD Investigation of Compact and Low-Voltage Waveguide-Integrated Plasmonic Ge/SiGe Multiple Quantum Wells Photodetectors

We report on 3-D FDTD simulation of waveguide-integrated plasmonic Ge/SiGe MQWs photodetectors. Despite several significant works on Ge/SiGe MQW optical modulators, Ge/SiGe MQW photodetectors still show improvable performance, limiting the potential to employ them for both optical modulation and detection. In this paper, we investigate the use of plasmonic concept to enhance electromagnetic field confinement inside the Ge/SiGe MQWs absorbing region with a view to having a compact and low-voltage waveguide-integrated Ge/SiGe MQWs photodetectors. Optical responsivities in term of applied electric fields, device dimensions of width and length, optical bandwidth, fabrication misalignment, and number of QWs periods are taken into account. The investigation shows that using plasmonic enhancement, a waveguide-integrated Ge/SiGe MQWs photodetector that is as short as 5 μm could be obtained with comparable responsivity and bias voltage values to some of the state-of-the-art bulk Ge-based devices, increasing the potential usage of Ge/SiGe MQWs for both optical modulation and detection in low-energy optical interconnects.

A Two-Dimensional Model for the Field-Plate Design of High-Voltage Transistor

The field plate (FP) is a widely adopted concept and has been commonly used for high-voltage (HV) transistors to increase the breakdown voltage without enlarging the device dimension. In this article, a 2-D mathematical equation is derived for the FP design of HV transistors which reveals the potential and the electric field distributions in the reduced-surface field (RESURF) region. From the derived mathematical model, the mechanism of the FP-induced electric field suppression for the HV transistors is completely explained as the FP can reduce the potential gradient ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E} = -\nabla \varphi $ </tex-math></inline-formula> ) caused by the dielectric thickness differences above the RESURF region. The potential and the electric field distributions of the RESURF region will change as the FP is inserted due to the dielectric thickness variations. The derived equations also explained the capacitive behaviors and quantitatively described the potential and electric field distributions in different configurations of the FP-assisted RESURF devices. The results obtained by the derived equation are found to be very much accurate compared with technology computer-aided design (TCAD) simulation results.

Investigation of Transient Two-Stage Thermal Equivalent RC Network of SOI-MOSFETs Using Nano Double-Pulse Measurement

The self-heating effect (SHE) of silicon-on-insulator (SOI) MOSFETs brings challenges to the measurement and modeling of transient electrothermal characteristics. For the first time, this study obtains the transient two-stage thermal equivalent RC network of SOI MOSFETs by nano double-pulse measurement combined with network identification by a deconvolution (NID) method. The two-stage model provides a comprehensive reference for the accumulation of residual heat under dynamic operation. We reveal that since the oxide layer acts as a thermal reservoir, the heat dissipation process can be divided into three phases according to thermal time constants. The results of geometry dependence of thermal parameters show that the gate length and width-to-length ratio ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${W}/{L}$ </tex-math></inline-formula> ) increase: the thermal resistance trend of both stages decreases, the one-stage thermal time constant increases, but the two-stage thermal time constant decreases. Also, as the scaling of device dimension and mutual thermal coupling, the thermal transient response boosts significantly.

Overview of Aging Mechanisms in Sige Hbts

This paper reviews the recent studies in hot carrier degradation mechanisms of SiGe HBTs under saturation mode and off-state operation. Reliability of these devices gets increased scrutiny as technological scaling drives down device dimensions. Even as the performance of these devices increases, the hot carrier generation and reaction kinetics concepts driving degradation in sensitive regions of the device remain the same. The new mechanisms discussed here can be broadly categorized using the physics of high-voltage or high-current electrical stress conditions that have been well-studied. Measurements and TCAD simulations suggest that voltage-limited mechanisms consistently see worse degradation at lower temperatures while current-limited mechanisms respond to both higher temperature and higher current density. These limitations must be carefully evaluated during the development of new technologies and circuits.