Device Leakage Research Articles

No more bonding, no more clamping, magnetically assisted membrane integration in microfluidic devices

The integration of porous membranes with microfluidic devices allows a simple but high-throughput mass transport control for numerous microfluidic applications, such as single-cell separation, sample analysis, and purification. In this study, we demonstrate a novel integration process of porous membranes into microfluidic devices by applying a magnetic field and hydrodynamically stabilizing them. This new approach simplifies the integration process by removing physicochemical bonding between membranes and microfluidic devices, but overcomes many practical issues observed in current methods, such as device leakage, membrane replacement, and membrane material selection. More importantly, our approach allows us to install membranes with diverse physicochemical features and spatial configurations into a single microfluidic device. This additional ability can significantly improve its performance and capability in applications. Finally, we successfully demonstrate the utilization of our membrane device for simple particle separation.

Potassium permanganate soak combined with a negative pressure drainage device for bone and soft tissue infection

Objective To analyze the clinical efficacy of potassium permanganate soak combined with a closed negative pressure drainage device for treatment of bone and soft tissue infection. Methods A retrospective analysis was performed of the 83 patients with bone and soft tissue infection who had been treated at Department of Orthopaedics, The Second People’s Hospital of Fuzhou from July 2010 to March 2017. They were 71 males and 12 females, aged from 15 to 77 years (median, 44 years). Of them, 47 were subjected to soak with 1∶5,000 potassium permanganate solution and 36 to soak with 1∶5,000 gentamycin solution before a negative pressure sealing drainage device was applied for them all. The 2 groups were compared in terms of complications (pain, drainage device blockage or leakage, wound bleeding, tube pressure ulcer, and new nosocomial infection), time for negative bacterial culture, time for drainage device removal, time for wound closure, healing rate and recurrence rate. Results There were no significant differences between the 2 groups in pain, drainage device blockage or leakage, wound bleeding, or tube pressure ulcer (P>0.05). The rate of new nosocomial infection was significantly lower in the potassium permanganate group (2.1%) than in the gentamicin group (13.9%). The time for negative bacterial culture, drainage device removal and wound closure in the potassium permanganate group (6 d, 12 d and 18.5±1.9 d, respectively) was all significantly shorter than in the gentamicin group (9 d, 15 d and 20.0±2.2 d, respectively) (P< 0.05). The healing rate for the potassium permanganate group (100%) was significantly higher than that for the gentamicin group (86.1%); the recurrence rate (0) for the former was significantly lower than that for the latter (13.9%) (P< 0.05). Conclusion Potassium permanganate soak combined with a negative pressure drainage device is effective, economical, convenient and safe for the treatment of bone and soft tissue infection, compared with gentamicin soak combined with the same device. Key words: Potassium permanganate; Negative-pressure wound therapy; Soft tissue infections; Bone

Leakage Models for High-Level Power Estimation

Leakage currents are one major concern when designing recent CMOS devices, making design for leakage at all stages of the design process mandatory. Early leakage optimization requires early leakage prediction, and for electronic system level design, this means estimation capabilities at register transfer (RT) level or above. Existing models are very accurate, but slow [transistor level such as Berkeley Simulator (BSIM)], or the slightly faster gate level models (such as the Liberty library), disregard relevant parameters. We present RT level leakage macro models, which are faster than recent gate level models, while preserving the accuracy of the transistor level models to a great extent. An estimation framework is proposed, describing the subthreshold, gate, and junction leakage of recent technology devices. The models are characterized using BSIM compact models and a Monte Carlo process variation description. Each varying BSIM parameter can be described. As an example of use, channel length, oxide thickness, and channel doping are regarded together with the temperature, supply voltage and body voltage. The final macro model needs less than a hundred parameters to capture the leakage behavior of an entire RT component and is still analytically describing the dependence to the process parameters. Compared to SPICE + BSIM, a model prediction is computed up to a hundred times faster for large RT components, and is, depending on the analyzed technology, within 2.1% (for 16-nm LP)–6.8% (for 65-nm bulk) deviation over a wide range of operating conditions and process variation settings.

Characterization and design optimization of heterojunction photodiodes comprising n-type ultrananocrystalline diamond/hydrogenated amorphous carbon composite and p-type Si

In this paper, we characterize and optimize design of a candidate ultraviolet photodiode based on nitrogen-doped ultrananocrystalline diamond hydrogenated amorphous carbon (UNCD/a-C:H) composite films grown on crystalline-Si substrates by coaxial arc plasma deposition. A comprehensive study including growth, fabrication, characterization, and modeling of the photodetector is presented here. The current-voltage characteristics of the device were reproduced and their critical parameters were extracted from a good matching between experimental and simulation results. A midgap acceptor-like defect state density of ~ 5 × 1017 cm−3 eV−1 was found to be the dominant defect in the UNCD/a-C:H film, in addition to an interface defect density of ~ 3 × 1013 cm−2 eV−1 at the interface of the UNCD/a-C:H film and the Si substrate. Experimental and simulation results showed that introducing an intrinsic UNCD/a-C:H layer in a pin heterostructure would significantly reduce the device leakage current and consequently improve its performance as an ultraviolet photodiode. Unoptimized fabricated devices exhibited a room temperature photoresponsivity of 135 mA/W measured under illumination of ultraviolet monochromatic light with a wavelength of 254 nm. The key parameters for optimized design of the device were extracted and investigated in details.

Observation of Hot Electron and Impact Ionization in N-Polar GaN MIS-HEMTs

This letter reports on the observation of hot-electron and impact-ionization mechanisms in N-polar GaN-based MIS-HEMTs designed for high frequency (RF) operation. Thanks to the extremely low gate leakage of such devices, we were able to demonstrate—for the first time—a correlation between electroluminescence (EL) and gate current in the semi-on state. In the semi-on state, the devices show a non-monotonic, bell-shaped behavior of the EL-versus- ${\text {V}}_{\text {GS}}$ and of the ${I}_{\text {G}}$ -versus- ${V}_{\text {GS}}$ characteristics, and the intensity of the EL signal is proportional to the ${I}_{G}\times {I}_{D}$ product. The results are experimental evidence for impact ionization: the related mechanisms are described in detail in the letter.

Analysis of Leakage Current Mechanism for Ni/Au Schottky Contact on InAlGaN/GaN HEMT

The gate leakage mechanism for InAlGaN/GaN high electron mobility transistors (HEMTs) is systematically studied using temperature‐dependent gate current–voltage characteristics. The electric field across the barrier layer is calculated through the extracted polarization charge and dielectric constant of the InAlGaN/GaN HEMT. The gate current of the InAlGaN/GaN HEMT is analyzed by fitting the experimental data using Themionic Emission (TE), Poole–Frenkel (PF), and Fowler–Nordheim (FN) tunneling. The results show that 1) reverse leakage current in the thin InAlGaN barrier layer is dominated by FN tunneling due to triangular barrier formation; 2) for thicker barrier layer, the reverse leakage current at low electric field (&lt;2.23 MV cm−1) is dominated by PF emission; 3) at high electric field near the threshold voltage the FN tunneling dominates. Extraction of effective barrier height by fitting the experimental data with models leads to the suggestion for the improvement of the device leakage current.

Clinical Evaluation of a Novel Intrarectal Device for Management of Fecal Incontinence in Bedridden Patients.

The primary objective of the study was to evaluate the safety and efficacy of a stool management kit (SMK) for containment of fecal incontinence in hospitalized bedridden patients. A single-group quasi-experimental study. Twenty bedridden adults who had at least 1 episode of fecal incontinence in the prior 24 hours participated in the study. The study setting was the neurological unit of the All India Institute of Medical Sciences in New Delhi, India. The study was carried out in 2 phases. The device was placed in situ for up to 24 hours in 10 patients during phase I of the study and up to 120 hours in an additional 10 patients during phase II. Participants were assessed for anorectal injury and peripheral device leakage on a 4- to 6-hourly basis. Sigmoidoscopy was performed to evaluate for any mucosal trauma or alteration of anorectal pathology after retrieval of the device. The device was successfully placed in all patients following the first attempt to place the device; 80% of patients retained the device until planned removal. The SMK diverted fecal matter without anal leakage in 174 (93.5%) out of 186 assessment points in a group of 20 patients. The devices remained in situ for 21 ± 0.2 and 84.5 ± 38.9 hours during phase I and phase II, respectively. None experienced anorectal bleeding, sphincter injury, or mucosal ulceration with device usage. Post-device sigmoidoscopy revealed erythema at the site of diverter placement in 2 participants. Study findings suggest that the SMK successfully diverted liquid to semiformed fecal exudate without peripheral device leakage in 93.5% of bedridden patients. No serious adverse events occurred. Additional research is needed to compare its effectiveness with that of currently available intrarectal balloon devices.

0.00035 mm 2 on‐chip leakage sensing unit for various devices in 10 nm FinFET process

An efficient on-chip leakage sensing unit is proposed, which is composed of four stages. Device under test (DUT) arrays include 16 types of transistors for leakage measurement. Threshold detector monitors the crossing point of inverter threshold causing the transition. Transition time is inversely proportional to the leakage current of the selected DUT. This time information of threshold detector is converted to voltage manner through the time-to-voltage converter with the diode stacked voltage generator. The generated voltage is transferred to voltage controlled oscillator (VCO) for frequency conversion which is the final output of leakage sensor. The proposed sensor provides leakage information of the various types of devices by using the same sub-circuit within on-chip. The prototype sensor occupies 0.00035 mm2 area and consumes 1200 μW with eight DUT arrays within a chip. Experimental results show the well-correlated frequency output with device leakage current.

The Free-Swimming Device Leakage Detection in Plastic Water-filled Pipes through Tuning the Wavelet Transform to the Underwater Acoustic Signals

The conventional fixed acoustic sensors leak detection methods have been demonstrated to be very practical for locating leakages in water distribution pipelines. However, these methods demand proper installation of sensors, and therefore cannot be implemented on buried long water distribution pipelines for condition assessment, early leak detection, and the estimation of leak size effect. Due to these limitations, a free-swimming device is developed. The free-swimming device with the potential of high acoustic sensitivity is capable of detecting the small underwater leakages in the plastic water-filled pipes. Despite the fact that a number of factors influence the underwater acoustic signals, such as water flow noise. Therefore, the interpretation of the leakage and influence of leakage size is considerably challenging from the underwater measured signals. The new method is proposed for reliable leakage detection by tuning the wavelet transform to underwater water acoustic signals. In this method, firstly, Short-Time Fourier Transforms (STFT) of underwater acoustic signals over a relatively long time-interval is monitored to capture the leakage-signals signature. The captured signals efficiently lead in the selection of mother wavelet (tuned wavelet) for the excellent signal localization in the time-frequency domain. Finally, the acoustic signals are analyzed in the tuned wavelet transform to detect the events. In this paper, the practical application of the proposed method, the controlled experiments are designed, and acoustic signals are collected from an experimental setup by launching the free-swimming device. The measured acoustic signals are used to identify the leakage-signals signature from unwanted interfering signals (instantaneous pipe vibrations, water flow noise, pipe's natural frequencies, and background noise). The evaluation of results validated that the free-swimming device and the tuned wavelet transform together can efficiently lead to reliable underwater leakage detection, as well as the influence of the leakage size in plastic water-filled pipes.

Characteristics of enhanced-mode AlGaN/GaN MIS HEMTs for millimeter wave applications

In this paper, an enhanced-mode (E-mode) AlGaN/GaN high electron mobility transistor (HEMT) was developed by using 4-inch GaN HEMT process. We designed and fabricated Emode HEMTs and characterized device performance. To estimate the possibility of application for millimeter wave applications, we focused on the high frequency performance and power characteristics. To shift the threshold voltage of HEMTs we applied the Al2O3 insulator to the gate structure and adopted the gate recess technique. To increase the frequency performance the e-beam lithography technique was used to define the 0.15 um gate length. To evaluate the dc and high frequency performance, electrical characterization was performed. The threshold voltage was measured to be positive value by linear extrapolation from the transfer curve. The device leakage current is comparable to that of the depletion mode device. The current gain cut-off frequency and the maximum oscillation frequency of the E-mode device with a total gate width of 150 um were 55 GHz and 168 GHz, respectively. To confirm the power performance for mm-wave applications the load-pull test was performed. The measured power density of 2.32 W/mm was achieved at frequencies of 28 and 30 GHz.

Graded channel doping junctionless MOSFET: a potential high performance and low power leakage device for nanoelectronic applications

In this paper, a graded channel doping paradigm is proposed to improve the nanoscale double gate junctionless DGJL MOSFET electrical performance. A careful mechanism study based on numerical investigation and a performance comparison between the proposed and conventional design is carried out. The device figures-of-merit, governing the switching and leakage current behavior are investigated in order to reveal the transistor electrical performance for ultra-low power consumption. It is found that the channel doping engineering feature has a profound implication in enhancing the device electrical performance. Moreover, the impact of the high-k gate dielectric on the device leakage performance is also analyzed. The results show that the proposed design with gate stacking demonstrates superior $$I_{{\textit{ON}}}/I_{{\textit{OFF}}}$$ ratio and lower leakage current as compared to the conventional counterpart. Our analysis highlights the good ability of the proposed design including a high-k gate dielectric for the reduction of the leakage current. These characteristics underline the distinctive electrical behavior of the proposed design and also suggest the possibility for bridging the gap between the high derived current capability and low leakage power. This makes the proposed GCD-DGJL MOSFET with gate stacking a potential alternative for high performance and ultra-low power consumption applications.

In brief

PAGE 908 A new approach to measuring fat content in the human body is presented in work from the US and Korea. Using electromagnetic reflectivity and conductivity of the abdominal layers of skin, fat and muscle they were able to measure the thickness of dielectric fat layers. This allows an analytical measurement of obesity using a cheap and mobile device. PAGE 930 Researchers in Korea present an efficient method for determining the electrical resistivity of pillar-shaped brittle thermoelectric materials, such as Bi2Te3. Their proposed apparatus measures electrical resistivity without a weld or paste contact, avoiding physical damage and chemical contamination of the contacted layers. The method makes it possible to reproduce and evaluate samples, enabling inspection for mass production applications. A microwave approach to measuring abdomenal fat content and distribution PAGE 939 In work from China, researchers demonstrate the fabrication of a stable dual-wavelength AlGaInAs/InP microsquarelaser for Terahertz (THz) wave transmission. Introducing a dual wavelength signal to an erbium doped fibre amplifier and photodiode mixer, achieved a beat signal output in the THz range. The team believe this work indicates the potential of present dual wavelength microsquare lasers for compact integrated THz sources. A new approach for measuring the electrical resistivity of brittle thermoelectric materials PAGE 941 Researchers in the UK have developed a theoretical model for calculating the efficiency of a segmented transmitter scheme for dynamic wireless power transfer electric vehicles; where power is provided to the vehicles on the move. The size and separation of neighbouring transmission rails were determined to be key factors in optimising power transfer efficiencies irrespective of vehicle speed. Dual-wavelength AlGaInAs/InP microsquarelasers capable of THz wave transmission PAGE 960 Work from India proposes a new tunnel-field effect transistor that reduces current leakages of nano-scaled MOSFET devices. The fabricated device consists of a double-gated dual metal structure. Charge separation was achieved through differences in the electronic properties of the interfaced metals in a plasma diode scheme without material doping, providing better device reliability. Optimising the design of dynamic wireless power transfer for moving electric vehicles The new tunnel-field effect transistor is designed to prevent current leakages in nano-scale MOSFET devices

A self-standing hydrogel neutral electrolyte for high voltage and safe flexible supercapacitors

Abstract The development of safe flexible supercapacitors implies the use of new non-liquid electrolytes for avoiding device leakage which combine mechanical properties and electrochemical performance. In this sense, hydrogel electrolytes composed of a solid non-conductive matrix holding an aqueous electrolytic phase are a reliable solution. In this work, we propose a green physical route for producing self-standing hydrogel films from a PVA polymer based on the freezing/thawing method without using chemical cross-linking agents. Moreover, a neutral electrolytic phase as Na 2 SO 4 is used for reaching higher cell voltages than in an acidic or basic electrolyte. Such new PVA-Na 2 SO 4 hydrogel electrolyte, which also acts as separator, allows reaching voltages windows as high as 1.8 V in a symmetric carbon/carbon supercapacitor with optimal capacitance retention through thousands of cycles. Additionally, in reason of the fast mobility of the ions inside of the polymeric matrix, the hydrogel electrolyte based supercapacitor keeps the power density of the liquid electrolyte device.

Efficiency test of current carotid embolic protection devices

Embolic protection devices were developed to reduce the risk of stroke during carotid artery stenting. The aim of this study was to test the capture efficiency of five embolic protection devices under reproducible in vitro conditions. The setup consisted of silicone tubes representing the vessel modeling round and oval cross sections. Spherical polystyrene particles (150 μm, COOH-coating) were used to simulate the plaque. The particles were inserted in a clean water circuit and either captured by the device or collected in a glass filter. The missed particles were counted by laser obscuration as a measure of device leakage. The systems Angioguard RX, RX Accunet, FiberNet, FilterWire EZ and EmboshieldNAV were analyzed. At the round cross section, FilterWire EZ demonstrated the highest capture efficiency (0% of missed particles) and RX Accunet the lowest, at 34%. The amount of leaked particles increased to 22% for FilterWire EZ and 89% for Angioguard RX during the test with the oval cross profile.

Highly Efficient and Stable Perovskite Solar Cells by Interfacial Engineering Using Solution-Processed Polymer Layer

Solution-processed organo-lead halide perovskite solar cells with deep pinholes in the perovskite layer lead to shunt-current leakage in devices. Herein, we report a facile method for improving the performance of perovskite solar cells by inserting a solution-processed polymer layer between the perovskite layer and the hole-transporting layer. The photovoltaic conversion efficiency of the perovskite solar cell increased to 18.1% and the stability decreased by only about 5% during 20 days of exposure in moisture ambient conditions through the incorporation of a poly(methyl methacrylate) (PMMA) polymer layer. The improved photovoltaic performance of devices with a PMMA layer is attributed to the reduction of carrier recombination loss from pinholes, boundaries, and surface states of perovskite layer. The significant gain generated by this simple procedure supports the use of this strategy in further applications of thin-film optoelectronic devices.

SRAM Cell Leakage Control Techniques for Ultra Low Power Application: A Survey

Low power supply operation with leakage power reduction is the prime concern in modern nano-scale CMOS memory devices. In the present scenario, low leakage memory architecture becomes more challenging, as it has 30% of the total chip power consumption. Since, the SRAM cell is low in density and most of memory processing data remain stable during the data holding operation, the stored memory data are more affected by the leakage phenomena in the circuit while the device parameters are scaled down. In this survey, origins of leakage currents in a short-channel device and various leakage control techniques for ultra-low power SRAM design are discussed. A classification of these approaches made based on their key design and functions, such as biasing technique, power gating and multi-threshold techniques. Based on our survey, we summarize the merits and demerits and challenges of these techniques. This comprehensive study will be helpful to extend the further research for future implementations.

Analysis of TID Process, Geometry, and Bias Condition Dependence in 14-nm FinFETs and Implications for RF and SRAM Performance

Total ionizing dose results are provided, showing the effects of different threshold adjust implant processes and irradiation bias conditions of 14-nm FinFETs. Minimal radiation-induced threshold voltage shift across a variety of transistor types is observed. Off-state leakage current of nMOSFET transistors exhibits a strong gate bias dependence, indicating electrostatic gate control of the sub-fin region and the corresponding parasitic conduction path are the largest concern for radiation hardness in FinFET technology. The high- $V_{\textit {th}}$ transistors exhibit the best irradiation performance across all bias conditions, showing a reasonably small change in off-state leakage current and $V_{\textit {th}}$ , while the low- $V_{\textit {th}}$ transistors exhibit a larger change in off-state leakage current. The “ worst-case” bias condition during irradiation for both pull-down and pass-gate nMOSFETs in static random access memory is determined to be the on-state ( $V_{\textit {gs}}=V_{\textit {dd}}$ ). We find the nMOSFET pull-down and pass-gate transistors of the SRAM bit-cell show less radiation-induced degradation due to transistor geometry and channel doping differences than the low- $V_{\textit {th}}$ transistor. Near-threshold operation is presented as a methodology for reducing radiation-induced increases in off-state device leakage current. In a 14-nm FinFET technology, the modeling indicates devices with high channel stop doping show the most robust response to TID allowing stable operation of ring oscillators and the SRAM bit-cell with minimal shift in critical operating characteristics.

A Comprehensive Computational Modeling Approach for AlGaN/GaN HEMTs

This paper for the first time presents a comprehensive computational modeling approach for AlGaN/GaN high electron mobility transistors. Impact of the polarization charge at different material interfaces on the energy band profile as well as parasitic charge across the epitaxial stack is modeled and studied. Furthermore, impact of surface and bulk traps on two-dimensional electron gas, device characteristics, and gate leakage is accounted in this paper. For the first time, surface states modeled as donor type traps were correlated with gate leakage. Moreover, a new approach to accurately model the forward gate leakage in Schottky gate devices is proposed. Finally, impact of lattice and carrier heating is studied, while highlighting the relevance of carrier heating, lattice heating, and bulk traps over the device characteristics. In addition to this, modeling strategy for other critical aspects like parasitic charges, quantum effects, S/D Schottky contacts, and high field effects is presented.

Architectural modifications for flexible supercapacitor performance optimization

We have developed material and architectural alternatives for flexible supercapacitors and investigated their effect on practical performance. The substrate alternatives include paperboard as well as various polyethylene terephthalate (PET) films and laminates, with aqueous NaCl electrolyte used in all devices. In all the supercapacitors, activated carbon is used as the active layer and graphite ink as the current collector, with various aluminium or copper structures applied to enhance the current collectors’ conductivity. The capacitance of the supercapacitors was between 0.05 F and 0.58 F and their equivalent series resistance (ESR) was from <1 Ω to 14 Ω, depending mainly on the current collector structure. Furthermore, leakage current and selfdischarge rates were defined and compared for the various architectures. The barrier properties of the supercapacitor encapsulation have a clear correlation with leakage current, as was clearly shown by the lower leakage in devices with an aluminium barrier layer. A cycle life test showed that after 40000 charge-discharge cycles the capacitance decreases by less than 10%.

Dislocation-Induced Punchthrough Causing Drain-to-Source Leakage Current in Power VD MOSFET Structures

A detailed characterization of the leakage in semiconductor devices is essential for proper adjustment of the manufacturing process in order to eliminate the leakage. Subsurface punchthrough was determined as the leakage current mechanism in the power vertical double-diffused metal–oxide–semiconductor field-effect-transistor, and the quadratic dependence of the drain current was confirmed for the leakage caused by the punchthrough. A failure analysis revealed a large number of dislocations located in the corners of transistor cells. The majority of the detected dislocations were electrically inactive. Dislocation depth measurement indicated that only a small number of the dislocations penetrated deep into the channel, i.e., penetrated from source area to the boron-doped p− transistor channel. The transistor channel shortening caused by the enhanced phosphorus diffusion along the dislocations was determined as the root cause of the leakage. The diffusion spikes of the phosphorus atoms lengthened the n+ source layer, and the interface of the n+ and p− layer was shifted into the transistor channel at the site of the dislocation. Manufacturing process experiments related to the channel lengthening and the channel doping confirmed the theory of the dislocation-induced channel shortening. The occurrence of dislocations was attributed to the surface stress induced by the improper conditions of oxide growing and plasma etching in the affected regions.