electrical measurements
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2022 ◽  
Vol 12 (1) ◽  
Author(s):  
James C. Gallagher ◽  
Mona A. Ebrish ◽  
Matthew A. Porter ◽  
Alan G. Jacobs ◽  
Brendan P. Gunning ◽  
...  

AbstractTo improve the manufacturing of vertical GaN devices for power electronics applications, the effects of defects in GaN substrates need to be better understood. Many non-destructive techniques including photoluminescence, Raman spectroscopy and optical profilometry, can be used to detect defects in the substrate and epitaxial layers. Raman spectroscopy was used to identify points of high crystal stress and non-uniform conductivity in a substrate, while optical profilometry was used to identify bumps and pits in a substrate which could cause catastrophic device failures. The effect of the defects was studied using vertical P-i-N diodes with a single zone junction termination extention (JTE) edge termination and isolation, which were formed via nitrogen implantation. Diodes were fabricated on and off of sample abnormalities to study their effects. From electrical measurements, it was discovered that the devices could consistently block voltages over 1000 V (near the theoretical value of the epitaxial layer design), and the forward bias behavior could consistently produce on-resistance below 2 mΩ cm2, which is an excellent value considering DC biasing was used and no substrate thinning was performed. It was found that high crystal stress increased the probability of device failure from 6 to 20%, while an inhomogeneous carrier concentration had little effect on reverse bias behavior, and slightly (~ 3%) increased the on-resistance (Ron). Optical profilometry was able to detect regions of high surface roughness, bumps, and pits; in which, the majority of the defects detected were benign. However a large bump in the termination region of the JTE or a deep pit can induce a low voltage catastrophic failure, and increased crystal stress detected by the Raman correlated to the optical profilometry with associated surface topography.


Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 97
Author(s):  
Francisco M. Espinosa ◽  
Manuel R. Uhlig ◽  
Ricardo Garcia

Silicon nanowire (SiNW) field-effect transistors (FETs) have been developed as very sensitive and label-free biomolecular sensors. The detection principle operating in a SiNW biosensor is indirect. The biomolecules are detected by measuring the changes in the current through the transistor. Those changes are produced by the electrical field created by the biomolecule. Here, we have combined nanolithography, chemical functionalization, electrical measurements and molecular recognition methods to correlate the current measured by the SiNW transistor with the presence of specific molecular recognition events on the surface of the SiNW. Oxidation scanning probe lithography (o-SPL) was applied to fabricate sub-12 nm SiNW field-effect transistors. The devices were applied to detect very small concentrations of proteins (500 pM). Atomic force microscopy (AFM) single-molecule force spectroscopy (SMFS) experiments allowed the identification of the protein adsorption sites on the surface of the nanowire. We detected specific interactions between the biotin-functionalized AFM tip and individual avidin molecules adsorbed to the SiNW. The measurements confirmed that electrical current changes measured by the device were associated with the deposition of avidin molecules.


2022 ◽  
Vol 17 (01) ◽  
pp. C01044
Author(s):  
X. Llopart ◽  
J. Alozy ◽  
R. Ballabriga ◽  
M. Campbell ◽  
R. Casanova ◽  
...  

Abstract Timepix4 is a 24.7 × 30.0 mm2 hybrid pixel detector readout ASIC which has been designed to permit detector tiling on 4 sides. It consists of 448 × 512 pixels which can be bump bonded to a sensor with square pixels at a pitch of 55 µm. Like its predecessor, Timepix3, it can operate in data driven mode sending out information (Time of Arrival, ToA and Time over Threshold, ToT) only when a pixel has a hit above a pre-defined and programmable threshold. In this mode hits can be tagged to a time bin of <200 ps and Timepix4 can record hits correctly at incoming rates of ∼3.6 MHz/mm2/s. In photon counting (or frame-based) mode it can count incoming hits at rates of up to 5 GHz/mm2/s. In both modes data is output via between 2 and 16 serializers each running at a programmable data bandwidth of between 40 Mbps and 10 Gbps. The specifications, architecture and circuit implementation are described along with first electrical measurements and measurements with radioactive sources. In photon counting mode X-ray images have been taken at a threshold of 650 e− (with <10 masked pixels). In data driven mode images were taken of ToA/ToT data using a 90Sr source at a threshold of 800 e− (with ∼120 masked pixels).


2022 ◽  
Vol 575 ◽  
pp. 121171
Author(s):  
Ankita Srivastava ◽  
Somnath Roy ◽  
Neeraj Mehta ◽  
A. Dahshan ◽  
S.D. Sharma

2021 ◽  
Author(s):  
Borislav Vasic ◽  
Uros Ralevic ◽  
Sonja Aškrabić ◽  
Davor Čapeta ◽  
Marko Kralj

Abstract Properties of van der Waals (vdW) heterostructures strongly depend on the quality of the interface between two dimensional (2D) layers. Instead of having atomically flat, clean, and chemically inert interfaces without dangling bonds, top-down vdW heterostructures are associated with bubbles and intercalated layers (ILs) which trap contaminations appeared during fabrication process. We investigate their influence on local electrical and mechanical properties of MoS2/WS2 heterostructures using atomic force microscopy (AFM) based methods. It is demonstrated that domains containing bubbles and ILs are locally softer, with increased friction and energy dissipation. Since they prevent sharp interfaces and efficient charge transfer between 2D layers, electrical current and contact potential difference are strongly decreased. In order to reestablish a close contact between MoS2 and WS 2 layers, vdW heterostructures were locally flattened by scanning with AFM tip in contact mode or just locally pressed with an increased normal load. Subsequent electrical measurements reveal that the contact potential difference between two layers strongly increases due to enabled charge transfer, while local I/V curves exhibit increased conductivity without undesired potential barriers.


2021 ◽  
Author(s):  
D. Ben Jemia ◽  
M. Karyaoui ◽  
M. A. Wederni ◽  
A. Bardaoui ◽  
M. V. Martinez-Huerta ◽  
...  

Abstract This work investigate the influence of Silver Plasmon and reduced graphene oxide (rGO) on the photoelectrochemical performance (PEC) of ZnO thin films synthesized by the sol-gel method. The physicochemical properties of the obtained photo-anodes were systematically studied using several characterization techniques. The X-ray diffraction analysis showed that all samples presented hexagonal Wurtzite structure with apolycrystalline nature. Raman and EDX studies confirmed the existence of both Ag and rGO in ZnO: Ag/rGO thin films. The estimated grain size obtained from (SEM) analysis decreased with Ag doping, then increased to a maximum value after rGO addition. The UV-vis transmission spectra of the as-prepared ZnO: Ag and ZnO: Ag/rGO thin films have shown a reduction in the visible range with a redshift at the absorption edges. The bandgaps were estimated to be around 3.17, 2.7, and 2.52 eV for ZnO, ZnO: Ag, and ZnO: Ag/rGO, respectively. Moreover, the electrical measurements revealed that the charge exchange processes were enhanced at the ZnO: Ag/rGO/electrolyte interface, accompanied by an increase in the (PEC) performance compared to ZnO and ZnO: Ag photo-anodes. Consequently, the photocurrent density of ZnO: Ag/rGO (0.2 mA.cm-2) was around 4 and 2.22 times higher than photo-anodes based on undoped ZnO (0.05 mA.cm-2) and ZnO: Ag (0.09 mA.cm-2), respectively. Finally, from the flat band potential and donor density, deduced from the Mott-Schottky, it was clear that all the samples were n-type semiconductors with the highest carrier density for the ZnO: Ag/rGO photo-anode.


Author(s):  
Yury V. LISAKOV ◽  
Olga V. LAPSHINOVA ◽  
Nikolay M. PUSHKIN ◽  
Viktor P. KONOSHENKO ◽  
Nikolay V. MATVEEV ◽  
...  

The paper presents the results of analysis of electrical measurements performed in the space experiment "Impulse (stage 1)" on the Service module of the ISS RS. This experiment investigated the effects of the interaction of the charged component of the ionosphere to the surface of large KA, which is the ISS. This paper analyses the measurement of quasi-stationary electric field and current leakage, was, respectively, sensors of the vibration type and flat probes from the Complex control electrophysical parameters (CCEP), developed by SPJ MT. To study the dependence of measurements from the ionosphere flow direction to the surface of the ISS RS was installed two sets of sensors with the direction of the angle of "visibility" in the Nadir (towards the Earth) and to "satellite footprint " (against the velocity vector of the ISS). Carried out analysis of common regularities measurements depending on the sun-shadow environment on orbit ISS motions and depending on current geophysical dynamics of the ionosphere. Massive the measurements including more than 170 telemetric sessions were analyzed. More than 11000 hours of measurements current of leakage (or runoff current) and measurements of quasi-stationary electric field with discretization 1s and UT binding to each point were analysed. The data measurements, geophysical and orbital data were collected in an electronic album. It is shown that experimental data correlate with the crossing time of the ISS boundaries known geophysical structures: the noon Meridian, the Main ionospheric failure (MIF), the boundaries diffuse intrusion (BDI), the Equatorial Geomagnetic anomaly (EA). In this regard, despite the specificity of the ISS (the spacecraft super big sizes, the most complex spatial configuration) similar measurements, nevertheless, are quite suitable for monitoring researches of some features of an ionosphere at the level of F2 layer with a temporary scale from 1s and can be used for more detailed study of the geophysical structures and related effects in the ionosphere. In addition, the results obtained can be used for the analysis of disturbances of electromagnetic conditions near the surface of the ISS RS, for monitoring potential and currents of leakage on the surface of the ISS. Keywords: electrophysical measurements, sensors of the vibration type, flat probes, electric field, current leakage, geophysical structure, ionosphere


Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 220
Author(s):  
Jinxia Gao ◽  
Longjun Liu ◽  
Zhiwen Su ◽  
Haitao Wang

Bite force measurement is an important parameter when checking the function and integrity of the masticatory system, whereas it is currently very difficult to measure bite force during functional movement. Hence, the purpose of this study is to explore the potential technique and device for the measurement and intervention of the continuous bite forces on functional and dynamic occlusal condition. A portable biosensor by sandwich technique was designed, and the validity, reliability, and sensitivity were determined by mechanical pressure loading tests; meanwhile, the pressure signal is acquired by, and transmitted to, voltage changes by the electrical measurements of the sensors. The result is that, when the mechanical stress detection device is thicker than 3.5 mm, it shows relatively ideal mechanical properties; however, when the thickness is less than 3.0 mm, there is a risk of cracking. Mechanical stress changing and voltage variation had a regularity and positive relationship in this study. The mechanical stress-measuring device made by medical and industrial cross has a good application prospect for the measurement of bite force during function.


Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 183
Author(s):  
Panagiotis S. Karagiannopoulos ◽  
Nikolaos M. Manousakis ◽  
Constantinos S. Psomopoulos

The design of longer-lasting products, such as domestic electric appliances, is a key-stone approach of the circular economy to reduce the use of non-reusable materials and the number of wastes to be managed at the end of the product’s life as well as to extend it. The manufacturing of modern electric appliances includes the incorporation of printed circuit boards (PCBs). PCBs provide mechanical support and electrically connect electrical or electronic components using conductive trackpads and other features etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate. This paper proposes a PCB maintenance framework, fully compliant with the “Right to Repair” concept, considering the impact of their aging failures based on measurements made on them, as well as the repair and replacement costs of their components. Herein, we present an algorithm that assesses the problem of handling the repair and replacement cost corresponding to specific failures while ensuring that the total cost of repair does not exceed a predefined value. This is achieved through an integer linear programming (ILP) formulation which maximizes the benefit to the life expectancy, Li, of an appliance, constrained by a customer’s limited budget. The proposed methodology is tested with different PCBs and considers different types of appliances. More specifically, two cases concerning PCBs of washing and dishwasher machines are studied to examine the dependency of the solutions on the aging rate of their various components. The simulation results show that considering a medium budget, after 3 years, we can achieve a health benefit of 92.4% for a washing machine’s PCB, while for a dishwasher’s PCB, the health benefit drops to 86.3%.


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