Microstructure of Grain Boundary Junctions in Bicrystal High-Tc Superconductor SQUIDs and its Relation with the Device Noise

1997 ◽  
Vol 3 (S2) ◽  
pp. 667-668
Author(s):  
Y. Huang ◽  
L. Lee ◽  
M. Teepe ◽  
K. L. Merkle ◽  
K. Char
Keyword(s):  
Grain Boundary ◽  
Quantum Interference ◽  
Underlying Mechanism ◽  
Low Noise ◽  
Noise Performance ◽  
Ion Milling ◽  
High Tc ◽  
Ybco Films ◽  
Extreme Sensitivity ◽  
Non Destructive

Superconductor Quantum Interference Devices (SQUIDs), because of their extreme sensitivity to magnetic fields and radiation, have found important applications in biomagnetism, non-destructive evaluation and geophysics. One problem in the application of high-Tc SQUIDs is their noise performance. Recently, considerable progress has been made in reducing the noise. To understand the underlying mechanism, it is important to identify the microstructural origin of the junction noise.In this work actual SQUIDs of good and poor noise performance are studied and compared by TEM. The devices were made by epitaxially growing YBa2Cu3O7-x (YBCO) films using laser ablation on 24° SrTiO3 bi-crystal substrates. The TEM samples were prepared by polishing and ion milling. The TEM observation was performed on a JEOL EM-4000EXII and a Hitachi H-9000 microscope.Observation shows that the YBCO films and the grain boundary junctions (GB J) in the low-noise devices are in good quality. The microstructure of the films and the boundaries in the films are shown in fig. 1 and 2.

Low Noise Directly-Coupled High Tc dc Superconducting Quantum Interference Device Magnetometers for Magnetocardiogram

1998 ◽  
Vol 37 (Part 2, No. 11A) ◽  
pp. L1308-L1311 ◽  
Author(s):  
Hyukchan Kwon ◽  
In-Seon Kim ◽  
Yong-Ho Lee ◽  
Jin-Mok Kim ◽  
Yong Ki Park ◽  
...  
Keyword(s):  
Quantum Interference ◽  
Low Noise ◽  
Superconducting Quantum Interference Device ◽  
High Tc ◽  
Superconducting Quantum Interference

High-Tc SQUID magnetometer with grain boundary junctions and its application in non-destructive evaluation

2000 ◽  
Vol 329 (2) ◽  
pp. 102-108 ◽  
Author(s):  
K Chen ◽  
L Chen ◽  
T Yang ◽  
J.P Wang ◽  
P.J Wu ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Squid Magnetometer ◽  
High Tc ◽  
Non Destructive Evaluation ◽  
Non Destructive

High resolution STEM imaging study on high Tc superconductor YBa2CuaO7-x

1988 ◽  
Vol 46 ◽  
pp. 882-883
Author(s):  
H.-J. Ou ◽  
J. M. Cowley
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Grain Boundary ◽  
Strong Field ◽  
Imaging Study ◽  
Structure Defects ◽  
High Tc ◽  
High Tc Superconductor ◽  
Diffraction Patterns ◽  
Lattice Planes

Using the dedicate VG-HB5 STEM microscope, the crystal structure of high Tc superconductor of YBa2Cu3O7-x has been studied via high resolution STEM (HRSTEM) imaging and nanobeam (∽3A) diffraction patterns. Figure 1(a) and 2(a) illustrate the HRSTEM image taken at 10' times magnification along [001] direction and [100] direction, respectively. In figure 1(a), a grain boundary with strong field contrast is seen between two crystal regions A and B. The grain boundary appears to be parallel to a (110) plane, although it is not possible to determine [100] and [001] axes as it is in other regions which contain twin planes [3]. Following the horizontal lattice lines, from left to right across the grain boundary, a lattice bending of ∽4° is noticed. Three extra lattice planes, indicated by arrows, were found to terminate at the grain boundary and form dislocations. It is believed that due to different chemical composition, such structure defects occur during crystal growth. No bending is observed along the vertical lattice lines.

Advanced Non-Destructive Fault Isolation Techniques for PCB Substrates Using Magnetic Current Imaging and Terahertz Time Domain Reflectometry

2018 ◽  
Author(s):  
Daechul Choi ◽  
Yoonseong Kim ◽  
Jongyun Kim ◽  
Han Kim
Keyword(s):  
Time Domain ◽  
Quantum Interference ◽  
Flip Chip ◽  
Imaging System ◽  
Time Domain Reflectometry ◽  
Fault Isolation ◽  
Magnetic Current ◽  
Isolation Techniques ◽  
Super Conducting ◽  
Non Destructive

Abstract In this paper, we demonstrate cases for actual short and open failures in FCB (Flip Chip Bonding) substrates by using novel non-destructive techniques, known as SSM (Scanning Super-conducting Quantum Interference Device Microscopy) and Terahertz TDR (Time Domain Reflectometry) which is able to pinpoint failure locations. In addition, the defect location and accuracy is verified by a NIR (Near Infra-red) imaging system which is also one of the commonly used non-destructive failure analysis tools, and good agreement was made.

scholarly journals Characterization of Chromium Compensated GaAs Sensors with the Charge-Integrating JUNGFRAU Readout Chip by Means of a Highly Collimated Pencil Beam

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1550
Author(s):  
Dominic Greiffenberg ◽  
Marie Andrä ◽  
Rebecca Barten ◽  
Anna Bergamaschi ◽  
Martin Brückner ◽  
...  
Keyword(s):  
Low Noise ◽  
State University ◽  
Noise Performance ◽  
X Ray ◽  
A Value ◽  
Resolution Capability ◽  
Sensor Properties ◽  
Pixel Pitch ◽  
Lower Noise

Chromium compensated GaAs or GaAs:Cr sensors provided by the Tomsk State University (Russia) were characterized using the low noise, charge integrating readout chip JUNGFRAU with a pixel pitch of 75 × 75 µm2 regarding its application as an X-ray detector at synchrotrons sources or FELs. Sensor properties such as dark current, resistivity, noise performance, spectral resolution capability and charge transport properties were measured and compared with results from a previous batch of GaAs:Cr sensors which were produced from wafers obtained from a different supplier. The properties of the sample from the later batch of sensors from 2017 show a resistivity of 1.69 × 109 Ω/cm, which is 47% higher compared to the previous batch from 2016. Moreover, its noise performance is 14% lower with a value of (101.65 ± 0.04) e− ENC and the resolution of a monochromatic 60 keV photo peak is significantly improved by 38% to a FWHM of 4.3%. Likely, this is due to improvements in charge collection, lower noise, and more homogeneous effective pixel size. In a previous work, a hole lifetime of 1.4 ns for GaAs:Cr sensors was determined for the sensors of the 2016 sensor batch, explaining the so-called “crater effect” which describes the occurrence of negative signals in the pixels around a pixel with a photon hit due to the missing hole contribution to the overall signal causing an incomplete signal induction. In this publication, the “crater effect” is further elaborated by measuring GaAs:Cr sensors using the sensors from 2017. The hole lifetime of these sensors was 2.5 ns. A focused photon beam was used to illuminate well defined positions along the pixels in order to corroborate the findings from the previous work and to further characterize the consequences of the “crater effect” on the detector operation.

Applying Independent Component Analysis to the Artifact Detection Problem in Magnetoencephalogram Background Recordings

2008 ◽  
pp. 84-92
Author(s):  
Javier Escudero ◽  
Roberto Hornero ◽  
Daniel Abásolo ◽  
Jesús Poza ◽  
Alberto Fernández
Keyword(s):  
Magnetic Fields ◽  
Quantum Interference ◽  
Brain Activity ◽  
External Noise ◽  
Low Noise ◽  
High Temporal Resolution ◽  
Artifact Detection ◽  
Mental Diseases ◽  
Electroencephalogram Eeg ◽  
The Brain

The analysis of the electromagnetic brain activity can provide important information to help in the diagnosis of several mental diseases. Both electroencephalogram (EEG) and magnetoencephalogram (MEG) record the neural activity with high temporal resolution (Hämäläinen, Hari, Ilmoniemi, Knuutila, & Lounasmaa, 1993). Nevertheless, MEG offers some advantages over EEG. For example, in contrast to EEG, MEG does not depend on any reference point. Moreover, the magnetic fields are less distorted than the electric ones by the skull and the scalp (Hämäläinen et al., 1993). Despite these advantages, the use of MEG data involves some problems. One of the most important difficulties is that MEG recordings may be severely contaminated by additive external noise due to the intrinsic weakness of the brain magnetic fields. Hence, MEG must be recorded in magnetically shielded rooms with low-noise SQUID (Superconducting QUantum Interference Devices) gradiometers (Hämäläinen et al., 1993).

Critical current in high Tc grain boundary junctions

1998 ◽  
Vol 84 (7) ◽  
pp. 3972-3979 ◽  
Author(s):  
Jerome A. Luine ◽  
Vladimir Z. Kresin
Keyword(s):  
Grain Boundary ◽  
Critical Current ◽  
High Tc
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