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Physical optics (PO) or Fresnel-Kirchhoff theory forms the base to solve the problem of diffraction over terrain or buildings, particularly when the terrain or buildings can be modeled as knife edges. Because the numerical integration required to solve the realistic problems is very time-consuming, physical optics is not commonly used in the original formulations for developing the related software...
An effective modeling of wave propagation over the spherical earth surface is of importance for target tracking, radar detection and wireless system analysis. This topic has been intensively studied in the past several decades. Meanwhile, the uniform theory of diffraction (UTD) for smooth convex surfaces has been developed and widely used in electromagnetic radiation and scattering. However, applying...
In this paper we report the progress on single quantum Hall devices for the resistance standards in NIM. We use the NIM-made device and the LEP-made device distributed to NIM by BIPM to calibrate a Tinsley 100 Ω transfer resistor using a cryogenic current comparator (CCC) at the filling factor k=2. The deviations of resistance values from the nominal value were −4.4808×10−6±3.5×10−9 by NIM-1 and −4...
NanoSQUIDs with Dayem nanobridge weak-link junctions were fabricated on single layer niobium film by focus ion beam(FIB) milling. The dimension of the nanobridge is less than 60 nm and the loop scale is from 400×400 nm to 2.5×20 μm. The working temperature range for this device was researched. The voltage-flux transfer properties were measured at different working temperatures.
Quantum Hall (QH) standard devices based on chemical vapor deposition (CVD) graphene have not shown properties as excellent as the one based on epitaxial graphene on SiC. This is because of the impurity, defects and inhomogeneity. In this paper, we demonstrate the progress on improving the quality of CVD graphene by the surface acidic processing and the low oxygen growth procedure.
In this paper we present a cryogenic test socket used for the quick device measurement at liquid Helium temperature. The chip under test could be easily installed inside the socket with the help of a clamp cover. Large amount of pins with 0.3mm diameter and 2.4mm length are utilized for electric contact inside the socket. Contact resistances as low as 0.2ohm are realized in a temperature range from...
We report in CPEM 2014 our effort towards SNS Josephson junction devices for the quantum voltage standard. SNS junction array device, with Nb as the superconductor material (S) and NbxSi1−x alloy as the barrier material (N), is fabricated and tested by NIM (National Institute of Metrology). The I–V characteristic curves of the junction arrays are measured and the experimental results are discussed.
We report in CPEM 2014 our latest results of the study of single quantum Hall device for the resistance standard in National Institute of Metrology, China (NIM). Experimental results indicate quantized Hall devices with satisfied longitudinal resistance, low contact resistance, and good breakdown current are obtained. Comparison of the quantum Hall resistance to a precise transfer resistance standard...
We reported the new design of quantum Hall array resistances. Two resistances, 100Ω and 1k𠄦, were achieved by series and parallel connections of single quantum Hall device based on the AlGaAs/GaAs heterostructure. The relative deviations from the nominal value were −3.42 parts of 108 for both design.
Large scale single-crystalline graphene was achieved on copper foils with CH4 as the precursor with a sandwich method. With a PMMA-assisted method, single-crystalline graphene was transferred to the marked SiO2/Si substrate. Quantum Hall devices will be fabricated by E-beam lithography and metallization. And, quantum Hall effect will be measured.
We report the fabrication and measurement of quantum Hall (QH) array devices based on GaAs/AlGaAs heterostructure in NIM. Three QH arrays, namely 2 Hall bars in series, 2 Hall bars in parallel, and 4 Hall bars in series are demonstrated. The low resolution preliminary measurement results are presented. The present resolution is limited by the measurement equipment and environment.
Reactive ion etching (RIE) is a common tool in micro- and nano-scale device fabrication. This paper presents experimental results of using the RIE tool to etch different films in Nb/NbxSi1−x/Nb Josephson junction array fabrication process in NIM.
Wafer-scale monolayer graphene film was synthesized on Cu foils by chemical vapor deposition in a 3-in thermal furnace. Graphene film was transferred to the surface of SiO2 (300 nm)/Si substrates using a polymer-assisted method. Hall bar structures were fabricated by lithography and E-beam deposition for the electrical property measurement. Perfect symmetrical ohmic resistance distribution was achieved...
We report in CPEM 2012 the preparation of the micromechanical cleavage (MC) and the chemical vapor deposition (CVD) graphene films and the fabrication of the quantum Hall resistance (QHR) devices on these films. Graphene films are on the SiO2/Si substrates. Spectroscopic Raman analysis indicates monolayer graphene films are obtained. Hall bar structures are formed on graphene films by e-beam lithography,...
We report in CPEM 2012 our effort towards SNS Josephson junction devices for the quantum voltage standard. A single-junction SNS device, with Nb as the superconductor material (S) and NbxSi1−x alloy as the barrier material (N), is fabricated and tested for the first time by NIM (National Institute of Metrology). A I–V characteristic curve of the junction is measured and the experimental results are...
Both SF6 and CF4 are plasma chemistries that are often used during dry etching in fabricating the niobium Josephson junctions. This paper presents the preliminary experimental results of using these two etches on etching Nb/NbxSi1−x/Nb Josephson junctions in NIM.
This paper presents a 2D to 3D conversion system from multiple views based on the computation of a sparse depth map. This method is able to deal with the multiple views obtained from uncalibrated hand-held cameras without prior knowledge of the camera parameters or scene geometry. The obtained reconstructed sparse depth maps of feature points in 3D scenes provide accurate relative depth information...
According to the emerging requirement in the nano fabrication field of obtaining the quantitative relationship between the nano structure and the color exhibited, a sphere size-color model has been proposed and proved by experiments in this paper. The photonic crystal structures of SiO2 Nano Spheres with different diameters are fabricated on glass substrate by self-assembly. Simulation is carried...
In this paper, we analyze the impact of configuration time on network performance in GMPLS based WDM networks, and propose a modified destination-initiated reservation (M-DIR) approach to reduce the impact.
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