Device Quality Research Articles

Gate-Defined Electron Interferometer in Bilayer Graphene.

We present an electron interferometer defined purely by electrostatic gating in an encapsulated bilayer graphene. This minimizes possible sample degradation introduced by conventional etching methods when preparing quantum devices. The device quality is demonstrated by observing Aharonov-Bohm (AB) oscillations with a period of h/e, h/2e, h/3e, and h/4e, witnessing a coherence length of many microns. The AB oscillations as well as the type of carriers (electrons or holes) are seamlessly tunable with gating. The coherence length longer than the ring perimeter and semiclassical trajectory of the carrier are established from the analysis of the temperature and magnetic field dependence of the oscillations. Our gate-defined ring geometry has the potential to evolve into a platform for exploring correlated quantum states such as superconductivity in interferometers in twisted bilayer graphene.

A nanogapped hysteresis-free field-effect transistor

We propose a semi-suspended device structure and construct nanogapped, hysteresis-free field-effect transistors (FETs), based on the van der Waals stacking technique. The structure, which features a semi-suspended channel above a submicrometer-long wedge-like nanogap, is fulfilled by transferring ultraclean boron nitride-supported MoS2 channels directly onto dielectric-spaced vertical source/drain stacks. Electronic characterization and analyses reveal a high overall device quality, including ultraclean channel interfaces, negligible electrical scanning hysteresis, and Ohmic contacts in the structures. The unique hollow FET structure holds the potential for exploiting reliable electronics as well as nanofluid and pressure sensors.

Highly improved passivation of PECVD p-type TOPCon by suppressing plasma-oxidation ion-bombardment-induced damages

Tunnel oxide passivated contact (TOPCon) integrated with a plasma-enhanced chemical vapor deposition (PECVD) boron-doped polysilicon has the potential to achieve high-efficiency and low-cost solar cells. In this contribution, we explore the feasibility of using PECVD technology to prepare high-performance p-type TOPCon (p-TOPCon) by growing two-step oxidation (TSO), i.e., a nitric acid oxidation (NAOS) SiOx without ion-bombardment followed by a plasma-assist N2O oxidation (PANO) SiOx layer. The experimental results reveal that for p-TOPCon structures on polished wafers with the conventional plasma oxidation SiOx, raising plasma oxidation powers to increase the thickness and oxidation degree of SiOx cannot ensure high-quality passivation due to the appearance of high-density defects caused by plasma ion-bombardment. In the presence of an additional NAOS SiOx layer, ion-bombardment-induced defects can be effectively suppressed, leading to a remarkable improvement in passivation properties. In detail, the optimal p-TOPCon with TSO SiOx achieves a maximum implied open-circuit voltage (iVoc) of ∼712 mV and a minimum single-sided saturation current density (J0,s) of ∼10 fA/cm2, manifesting an increment of iVoc by ∼10 mV, and a reduction of J0,s by ∼5 fA/cm2. Finally, the numerical simulations reveal that n-type Si solar cells featuring p-TOPCon rear junction and Al electrode could receive an efficiency of 24.6% based on the state-of-the-art device fabrication technology. In general, this work provides a new way to boost the passivation quality of PECVD p-TOPCon devices.

Using Data Science and Machine Learning to Predict the Failure Rate of Pin Diodes

GaN research is important to the development of next generation power conversion technology because its large Baliga figure of merit GaN gives it the potential to outperform SiC. Presently, commercialized GaN technology is based on lateral high electron mobility transistors (HEMTs); however, large areas would be required for high voltage applications thus there is motive to switch to vertical GaN. Current GaN substrate manufacturing technology is known to produce inconsistent quality with a varying concentration of defects. These defects are known to cause catastrophic device failure, thus there is motive to develop quick, non-destructive techniques to predict the quality of the wafer before undergoing the expensive fabrication process. This talk focuses on using data science and machine learning to predict the quality of the diodes.This work demonstrated that Raman spectroscopy can be used to detect high crystal stress points, which strongly correlates with an increased leakage current. Optical profilometry images can be used to detect defects that cause catastrophic failures; however, the presence of benign defects makes it difficult to predict the device quality using a simple algorithm. Thus, a machine learning algorithm relate optical profilometry images to device performance of subsequently processed device. The results showed that this algorithm was 91% accurate at predicting the forward bias behavior of devices, and it is possible that the devices it could accurately predict failures due to device processing errors.This work was supported by the Office of Naval Research.

A thermodynamic evaluation of metal halides for the recrystallization of Cu(In,Ga)Se2

AbstractCdTe films are deposited at low temperatures and recrystallized to photovoltaic device quality using CdCl2 treatments, leading to competitive manufacturing costs. Cu(In,Ga)Se2 (CIGS) typically requires high‐temperature, low‐rate depositions to produce high‐efficiency devices, resulting in higher costs. A similar metal halide treatment of CIGS has been demonstrated by us previously for some metal halide sources. To understand and optimize the process, a thermodynamic evaluation of candidate metal halides for such treatments is presented as a guide for their selection. By comparing bond dissociation energies, mono‐ and di‐halide compounds are proposed to be ideal compounds to act as transport agents. Known recrystallization and temperature reduction benefits by Ag alloying suggest that Ag halides should be used to aid transport of all species. The high vapor pressure and mobility of Ga compounds still pose a problem for metal halide treatment, resulting in Ga etching and removal of intentional Ga gradients. Less severe but similar issues with In compounds may occur. Cu compounds have low vapor pressures that may limit transport; however, Cu is highly mobile in CIGS, and recrystallization still occurs.

HEALTH CARE IN COVID-19 ENVIRONMENT: QUALITY ASSESSMENT OF MEDICAL VENTILATORS BY HEALTH CARE SYSTEM ENTITIES

The purpose of this article is to comprehend the functioning of the institute of public health in a pandemic and to conduct a research analysis of the opinions and judgments of medical workers and patients using medical ventilation devices. The national health care system faces a global challenge associated with the spread of COVID-19, which has exposed problem areas in its functioning, one of which is the quality and reliability of medical equipment. Medical ventilators are of vital importance, because their availability and quality determine the recovery of patients and their return to a familiar way of life. Ventilators are used in intensive care units and wards for treatment of severe complications of coronavirus infection. The main subjects of the health care system were interviewed using the semi-formalized interview method: doctors (n = 32) and patients (n = 16). The survey results showed that the quality of Russian devices requires significant improvement (oxygen tubes and flow sensors), and the main measures to improve the quality of medical care using ventilators are not only buying of imported medical equipment, but also strengthening quality control of domestic devices and creating real competitive environment of Russian manufacturers. In the context of the "new normalcy" on the Russian market of ventilators, it’s possible to transit from an import-oriented model to a national-state model with a significant proportion of medical products manufactured by Russian companies.

Broadband performance assessment of a microwave power transistor employing the real frequency technique

AbstractGeneration of proper source/load‐pull impedances for a selected active device is essential to design an RF power amplifier for optimum gain and power added efficiency. As they are obtained, these impedances may not be realizable network functions over the desired frequency band to yield the input and the output matching networks for the amplifier. Therefore, in this paper, first, we introduce a new method to test if a given impedance is realizable. Then, a novel “real frequency line‐segment technique” based numerical procedure is introduced to assess the gain‐bandwidth limitations of the given source and load impedances, which in turn results in the ultimate RF power‐intake and power‐delivery capacity of the amplifier. During the numerical performance assessments process, a robust tool called “virtual gain optimization” is presented. Finally, a new definition called “power performance product” is introduced to measure the quality of an active device. Examples are presented to test the realizability of the given source‐/load‐pull data and to assess the gain‐bandwidth limitations of the given source/load‐pull impedances for a 45 W‐GaN power transistor, namely, “Wolfspeed CG2H40045” over 0.8–3.8 GHz bandwidth.

Perses: A framework for the continuous evaluation of the QoS of distributed mobile applications

The increasing capabilities of mobile devices have led to the emergence of new paradigms exploiting them. These paradigms foster the onload and distribution of functionalities on mobile devices, allowing the development of distributed mobile applications. This distribution reduces the latency and the data traffic overhead and improves privacy. As in any other mobile application, their success largely depends on the quality of service (QoS) they offer. Nevertheless, the evaluation of distributed mobile applications is particularly complex due to the number, heterogeneity, and interactions between the devices involved. Current techniques allow developers to assess the quality of a single device, but they are not designed for highly heterogeneous, distributed, and collaborative environments. This paper presents a framework called Perses, which allows the creation of virtual scenarios with multiple heterogeneous mobile devices to launch end-to-end tests to evaluate not only each device but also the interactions among them. The framework was evaluated against a real deployment, showing that the behavior and the quality attributes measured are similar to those of the real deployment, allowing developers to evaluate these applications before launching them. Finally, Perses was integrated into a DevOps methodology to automate its execution and further facilitate its adoption by software companies.

Replay spoof detection using energy separation based instantaneous frequency estimation from quadrature and in-phase components

Replay attacks in speech are becoming easier to mount with the advent of high quality of recording and playback devices. This makes these replay attacks a major concern for the security of Automatic Speaker Verification (ASV) systems and voice assistants. In the past, auditory transform-based as well as Instantaneous Frequency (IF)-based features have been proposed for replay spoofed speech detection (SSD). In this context, IF has been estimated either by derivative of analytic phase via Hilbert transform, or by using high temporal resolution Teager Energy Operator (TEO)-based Energy Separation Algorithm (ESA). However, excellent temporal resolution of ESA comes with lacking in using relative phase information and vice-versa. To that effect, we propose novel Cochlear Filter Cepstral Coefficients-based Instantaneous Frequency using Quadrature Energy Separation Algorithm (CFCCIF-QESA) features, with excellent temporal resolution as well as relative phase information. CFCCIF-QESA is designed by exploiting relative phase shift to estimate IF, without estimating phase explicitly from the signal. To motivate and validate effectiveness of proposed QESA approach for IF estimation, we have employed information-theoretic measures, such as Mutual Information (MI), Kullback–Leibler (KL) divergence, and Jensen–Shannon (JS) divergence. The proposed CFCCIF-QESA feature set is extensively evaluated on standard statistically meaningful ASVSpoof 2017 version2.0 dataset. When evaluated on the ASVSpoof 2017 v2.0 dataset, CFCCIF-QESA achieves improved performance as compared to CFCCIF-ESA and CQCC feature sets on GMM, CNN, and LCNN classifiers. Furthermore, in the case of cross-database evaluation using ASVSpoof 2017 v2.0 and VSDC, CFCCIF-QESA also performs relatively better as compared to CFCCIF-ESA and CQCC on GMM classifier. However, for the case of self-classification on the ASVSpoof 2019 PA data, CFCCIF-QESA only outperforms CFCCIF-ESA. Whereas, on BTAS 2016 dataset, it performs relatively close to CFCCIF-ESA. Finally, results are presented for the case when the ASV system is not under attack.

Robust single- and multi-loudspeaker least-squares-based equalization for hearing devices

To improve the sound quality of hearing devices, equalization filters can be used to achieve acoustic transparency, i.e., listening with the device in the ear is perceptually similar to the open ear. The equalization filter needs to ensure that the superposition of the equalized signal played by the device and the signal leaking through the device into the ear canal matches a processed version of the signal reaching the eardrum of the open ear. Depending on the processing delay of the hearing device, comb-filtering artifacts can occur due to this superposition, which may degrade the perceived sound quality. In this paper, we propose a unified least-squares-based procedure to design single- and multi-loudspeaker equalization filters for hearing devices aimed at achieving acoustic transparency. To account for non-minimum phase components, we utilize a so-called group delay compensation. To reduce comb-filtering artifacts, we propose to use a frequency-dependent regularization. Experimental results using measured acoustic transfer functions from a multi-loudspeaker earpiece show that the proposed equalization filter design procedure results in robust acoustic transparency and reduces the impact of comb-filtering artifacts. A comparison between single- and multi-loudspeaker equalization shows that for both cases a robust equalization performance can be achieved for different desired open ear transfer functions.

Quantum transport in CVD graphene synthesized with liquid carbon precursor

Large-area high-quality graphene enabled by chemical vapor deposition (CVD) can possibly pave the path for advanced flexible electronics and spintronics. CVD-grown method utilizing liquid carbon precursor has recently been demonstrated as an appealing choice for mass graphene production, thanks to its low cost and safe operation. However, the quality of the graphene film has been the major obstacle for the implementation of the liquid-precursor-based CVD method. Here we report the growth of centimeter-scale easily-transferable single-layer graphene (SLG) using acetone as a liquid carbon precursor. The dry-transfer technique was used to prepare the graphene device. The typical mobility of the dry-transferred SLG device is as high as 12 500 cm2 V−1 s−1 at room temperature. Thanks to the high quality of the device, the robust quantum Hall effect can survive up to room temperature. The excellent device quality also enables us to observe the Shubnikov–de Haas oscillation in the low magnetic field regime and systemically study the leading scattering mechanism. We extracted both the transport scattering time τ t and the quantum scattering time τ q over a wide range of carrier density. The ratio of the scattering times suggests that the charged-impurity resided near the surface of the graphene restricted the device performance.

Quality and Regulation Standards for Ventilator as Medical Devices in India

The Drugs & Cosmetic act is meant to regularize safety & quality of medical devices, which is applied to all medical devices, implemented from 1st April 2020. Earlier 37 medical devices were regulated/ notified in India. The present study focuses on the devices which require regulations but still lack the quality check points for scrutiny from Central Drug standard control organization (CDSCO), Delhi. Furthermore, it aims to provide quality checklist for two upcoming devices (Ventilator) which is neither categorized nor regulated by Central Drug standard control organization, Delhi. Since the medical devices aid in diagnosing, treatment and palliative care, it is essential to check the quality such that it matches with the International standards. Post covid-19 outbreak ventilators have come under surveillance and notified as medical devices. The present study monitors all parameters for regulation of the ventilator. The survey based quality & regulation standards for ventilator as medical devices has been incorporated in this study.

Using a Wearable Device and Patient Reported Outcome to Evaluate the Influence of Sleep on Quality of Life Among Breast and Prostate Cancer Patients.

Few studies have used the combination of subjective and objective measures to investigate sleep problems as a primary outcome of concern in cancer patients. This study highlights the influence of sleep quality and duration on quality of life among breast and prostate cancer patients. Thirty-one participants were included in this study. Sleep quality and duration was assessed using a wearable actigraphy device and Pittsburgh Sleep Quality Index questionnaire. Quality of life was measured by European-Organization-For-Research-And-Treatment-Of-Cancer Quality of Life Questionnaire. t-test statistics further investigates the influence of sleep quality and duration with quality of life in participants. Results implied that those breast cancer patients who were poor sleepers and short sleepers showed greater deficits in areas of quality of life. In contrast, those prostate cancer patients who were long sleepers and good sleepers displayed poorer quality of life using actigraphy.

Reliability Analysis Based on Mixture of Lindley Distributions with Artificial Neural Network

AbstractThe study of reliability analysis of mixture model is essential in confirming the quality of devices, equipment, and electronic tube flops etc. In recent years, statisticians have developed more interest in mixture model research, notably in the last decade, without taking into account the issue of modeling the metrics of reliability of mixture models using artificial neural networks. In the present study, the influence of pertinent parameters on reliability metrics is studied. The effect of components and mixing parameters for failure function, reversed hazard rate function, mean time to failure, hazard rate function, mean inactivity time, mean residual life, reliability function, Mills Ratio profiles are plotted and discussed. A multi‐layer artificial neural network is developed using the numerical analysis results obtained using four different scenarios. The values extracted from the artificial neural network and the numerical findings of the reliability studies are extensively compared and examined. The deviation rates obtained for the developed artificial neural network model are obtained at values lower than 0.12%. The outcomes demonstrate that neural networks are a powerful and effective mathematical tool that can be used in the reliability analysis of mixing models.

0359 Clinical Performance Quality of a Precision Oral Appliance Made from Novel Medical Grade Class VI Material

Abstract Introduction Oral appliance therapy device quality is an important factor for successful, efficient treatment of Obstructive Sleep Apnea. Poor device quality, defined in this investigation as the remake rate, is costly. A previous investigation reports that 13% of oral appliance therapy devices required remakes, each costing an estimated $300 in lost productivity, fees for remakes, and three weeks of lost therapy. Other investigations associate poor quality with even higher costs and an increased propensity for the patient to discontinue treatment. Methods In this retrospective study design, quality data for 34,261 consecutively manufactured oral appliance therapy devices made from a novel medical grade class VI material was collected. Quality data was analyzed in total, and with 30-day and 60-day lag periods. The purpose of the lag periods was to account for the time between manufacture and delivery. Results Total remake rates were 1.2% (416/34,261). Total remake rates with a 30-day lag period were 1.3% (416/30,946). Total remakes with a 60-day lag period were 1.5% (416/26,964). Conclusion The clinical performance quality for a new precision oral appliance made from a novel medical grade class VI material is encouraging. Remake rates were between 1.2% and 1.5% depending on the lag period, which is directionally favorable in comparison with previously reported remake data. Support (If Any) Data provided by ProSomnus Sleep Technologies.

Home Monitoring of Glaucoma Using a Home Tonometer and a Novel Virtual Reality Visual Field Device: Acceptability and Feasibility

Our aim was to assess the acceptability and feasibility of iCare HOME tonometer (HT) and Virtual Field (VF) devices in the home monitoring of glaucoma. Prospective feasibility and acceptability study. Twenty patients (39 eyes) with primary open-angle glaucoma, open-angle glaucoma, ocular hypertension, or suspected glaucoma. Patients were trained and instructed to bring 2 devices home for 1 week and use the HT 4 times/day for 4 days and the VF 3 times total. For acceptability, we conducted satisfaction surveys and semistructured, qualitative interviews with a thematic analysis. Feasibility was assessed by device usage and quality of tests. Most patients (73.7%) felt that the HT was easy to use, and 100% of them found the HT useful. All patients (100%) felt that VF was easy to use, and 94.4% of them found the VF useful. All patients (100%) obtained acceptable intraocular pressure and completed a VF test at home. We identified 4 key themes, with 33 subthemes. The key themes include the following: (1) advantages of home monitoring; (2) difficulties with home monitoring; (3) future considerations in home monitoring; and (4) the experience of patients with glaucoma. The HT and VF were acceptable and feasible in a small cohort of motivated subjects. Patients were able to perform these tests proficiently at home, and they were generally enthused to obtain more data about their intraocular health, as it allowed them a heightened sense of security and insight about their chronic disease, as well as a reduction in foreseeable barriers to care. Home monitoring may also improve upon glaucoma care by enhancing patient empowerment and fostering community bonds. The VF should be further evaluated to ensure validity. Proprietary or commercial disclosure may be found after the references.

A Survey on the Intensity of Lighting in Elementary Schools of Bojnurd City

Background and Aim: Optimal lighting should create a balance between economy and the environment. In order to comply with safety and health principles of the staff, proper lighting of the work environment should be provided for everyday tasks. Inappropriate lighting conditions cause distortion of environmental visual information, and increase the likelihood of mistakes in the work. The quality of lighting is important for creating willingness to study, visual comfort, and productivity in the learning process of students. The subject of this research is the manner and intensity of lighting in schools, in the city of Bojnurd, in elementary education centers. It, also, tries to assess the quality of lighting schools, identify problems in school lighting systems, and provide appropriate solutions for improvement.
 Materials and Methods: This descriptive study was randomly selected in girl’s elementary schools of Bojnourd, during autumn of 1395, in 10 schools in different regions of the city. The overall lighting (natural and artificial) and natural light were measured individually, using the Hanger CE Lux Meter. Collected data, including total brightness, natural, and artificial of classes, were analyzed by SPSS software (version 18). For each class, the minimum, maximum and average brightness and standard deviation were calculated based on the lux. Also, the type of lamps, defective lamps, wall colors and the quality of devices and equipment were studied.
 Results: Results showed that in 90% of cases, the intensity of lighting was consistent with standard values, and in 10% of cases, the lighting intensity was not in accordance with the standard. In 87.57% of the cases, the type of lamps was suitable for lighting of the school and classes, and in 94.1% of the cases the lamps were burned out and defective.
 Conclusion: The lack of natural and artificial lighting in schools due to the incorrect placement of windows, inappropriate distribution of lamps, as well as the ratio of the surface to the window, are the causes of inappropriate status of lighting efficiency system.

Planning and Budgeting of Medical Devices Among Ethiopian Public Hospitals.

BackgroundPlanning and budgeting of medical devices allow a healthcare institution to properly use funds, acquire quality and efficient medical devices, and improve healthcare service delivery. The lack of proper policy in the procurement and management of medical devices causes inappropriate usage of funds and impedes the quality of a product. This study aimed to identify the current practices and gaps in the planning and budgeting of medical devices in Ethiopian public hospitals. In this study, an assessment was conducted in all regional public hospitals to assess the current status of medical device management, identify the gaps, and provide suggestions for areas of improvement.MethodsA descriptive cross-sectional design was used for the study assessment where a structured data collection tool was utilized to collect data. A multi-stage stratified random sampling proportionate to size technique was employed for the sampling of public hospitals in all regions of Ethiopia. The collected data was analyzed using SPSS version 26 software.ResultsThe availability of medical equipment development plans, budgeting, and spare parts procurement plans were found to be below 50% in public hospitals. It was also noted that 40.3% of hospitals do not prepare medical device technical specifications during procurement orders. Moreover, the engagement of biomedical engineers/technicians in the planning and procurement of medical devices was found to be below 50%.ConclusionThis assessment showed that there is a need for improvement in the development of procurement plans and preparation of technical specifications for medical devices in Ethiopian public hospitals. Developing policies and strategies for the proper use of funds in the procurement of medical devices, involving biomedical engineering professionals in the planning, procurement and use of medical devices could help to improve the quality, optimized utilization and efficiency of medical devices and ultimately enhance healthcare service delivery.

Unsupervised novelty pattern classification of shmoo plots for visualizing the test results of integrated circuits

Shmoo plots are visual tools for verifying the performance of integrated circuit devices, where each cell in a plot records whether the examined device operates normally under the test condition. When identifying the device state, the overall pass/fail pattern appearing in the shmoo plot is more important than the test results for individual conditions. Because similar shmoo plots indicate similar device characteristics, defect causes, and process peculiarities, engineers can analyze device quality and defect causes by classifying shmoo plot patterns. Most mass-produced devices have high and stable yields, whereas defect devices are incredibly scarce. If engineers classify numerous device plots manually at a semiconductor test site, significant time and resources will be required, and the result will likely vary based on the engineers’ experience. Therefore, shmoo plot usage is limited unless an automatic classification model is adopted. Moreover, training high-performance pattern classifiers that do not overfit the models is difficult because shmoo plots contain high-dimensional data and unlabeled, multiclass imbalanced datasets, where the number of defects is smaller than that of normal plots and pattern labels are seldom assigned. In this study, we propose a novel feature extraction process and a two-stage clustering process to distinguish novel shmoo plot patterns. Actual shmoo plots obtained from a wafer test stage are used to compare the experimental results obtained via the proposed method and conventional methods, and they verify the superiority of the proposed method.

Internet of Things: Security Vulnerabilities and Countermeasures

People's lives will be transformed by the Internet of Things (IoT), which connects everything from smart phones and sensors to the cloud to mobile apps and web-based controls. Security concerns are on the rise as the number of heterogeneous devices and data processing grows. Most IoT apps and devices are also well-known for their security flaws, making them vulnerable to many forms of attacks. To further complicate matters, threats have variable consequences on the device's security and quality. Unfortunately, enterprises are having difficulty determining which risks they face from their data assets and how to mitigate them. To better identify IoT security risks, this article has built a taxonomy based on the application domain and the design of the architecture. Servers, clients, IoT development boards, sensors, cloud subscriptions, and other components all play a role in this test setup. Vulnerability and network host scanning technologies are used to obtain raw data relevant to IoT-based smart city projects. This article also includes a mitigation approach for IoT network flaws.