共查询到20条相似文献,搜索用时 672 毫秒
1.
Telecommunication Systems - This paper analyzes the carrier-to-interference ratio (CIR) of the so-called shotgun cellular systems (SCSs) in $$\tau $$ dimensions ( $$\tau =1, 2,$$ and 3). SCSs are... 相似文献
2.
Petale Shrinivas Maurya Rakesh Kumar Thangaraj Jaisingh 《Wireless Personal Communications》2018,100(4):1707-1725
Wireless Personal Communications - Proper route selection between source and destination $$(s-d)$$ connection leads to efficient resource utilization which leads to the availability of resources... 相似文献
3.
J.D. Benson R.N. Jacobs J.K. Markunas M. Jaime-Vasquez P.J. Smith L.A. Almeida M. Martinka M.F. Vilela U. Lee 《Journal of Electronic Materials》2008,37(9):1231-1236
X-ray diffraction full-width at half-maximum (XRD FWHM), reflection high-energy electron diffraction (RHEED), and atomic force
microscopy (AFM) indicate a mosaic structure for molecular-beam epitaxy (MBE) (211)B CdTe/Si. AFM measurements indicate long,
thin, small-angle-disoriented grains for CdTe/Si epilayers. These disoriented grains are ~1 μm in the [] direction and are ~40 nm in the [] direction. The RHEED pattern in the [] direction depicts nearly ideal single-crystal periodicity. The RHEED pattern in the [] direction is indicative of small-angle-disoriented crystalline grains. Scanning electron microscopy (SEM), AFM, and XRD
measurements all indicate an approximate factor of 10 increase in the Everson etch pit density (EPD) over standard Nomarski
microscopy Everson EPD determination. 相似文献
4.
Hisashi Masui Samantha C. Cruz Shuji Nakamura Steven P. DenBaars 《Journal of Electronic Materials》2009,38(6):756-760
Inclined crystallographic planes of the wurtzite structure were investigated in comparison with the zincblende structure in
terms of surface geometry characteristics. The ball–stick model indicates that the semipolar surface possesses a surface polarity resembling the anion polarity, which agrees with the common experimental observations
of epitaxial growth preference for the cation-polarity surface over the surface. The wurtzite surface was found to share geometrical similarities with the zincblende {100} surface uniquely among the possible semipolar
planes. This finding encourages epitaxial growth on the plane of wurtzite semiconductors, e.g., GaN, with the potential of avoiding atomic step formations typically associated with
off-axis crystallographic planes. 相似文献
5.
Semiconductors - The deformation of a (0001)GaN epitaxial layer on the (11 $$\bar {2}$$ 0) sapphire a-cut is studied by X-ray diffractometry. Anisotropic-layer deformation is calculated by... 相似文献
6.
Tuerxun Ailihumaer Hongyu Peng Balaji Raghothamachar Michael Dudley Gilyong Chung Ian Manning Edward Sanchez 《Journal of Electronic Materials》2020,49(6):3455-3464
The inhomogeneous distributions of basal plane dislocations (BPDs) in PVT-grown 4H-SiC crystal boule due to internal stresses cause lattice plane bending, which strongly affect SiC-based device fabrication. The relationship between BPDs and local basal plane bending in 6-inch 4H-SiC substrates has been investigated. Synchrotron monochromatic beam x-ray topography (SMBXT) imaging shows black and white contrast of BPDs with Burgers vectors of opposite signs based on the principle of ray tracing. We have evaluated the net difference of BPDs with black and white contrast along both [11$$ \bar{2}$$0] and [1$$ \bar{1}$$00] radial directions on the Si face across multiple 6-inch diameter 4H-SiC substrates sliced from the same and different boules and predicted the nature (concave/convex) and amount of bending of the basal plane in these wafers. Line scans of 0008 reflection using high resolution x-ray diffractometry (HRXRD) has been carried out along the two directions to verify the nature of bending in these wafers. Results show quite different bending behavior along [11$$ \bar{2} $$0] and [1$$ \bar{1}$$00] directions, indicating that the Si face of 6-inch substrates creates non-isotropic bending on the basal plane. These observations are correlated quite well with net BPD density analysis. The physical shapes of the wafers were also measured to be not flat due to the surface effect. Quantitative analysis of the degree of basal plane bending based on the SMBXT data was carried out and found to be correlating well with the measured tilt angle from HRXRD. Existence of a high stress center was observed in one of the 6-inch wafers resulting in severe bending which is associated with both large bending angles and abrupt changes in lattice constants a and c. 相似文献
7.
Budunova K. A. Kravchenko V. F. Pustovoit V. I. 《Journal of Communications Technology and Electronics》2019,64(10):1095-1100
Journal of Communications Technology and Electronics - A method for synthesis of digital low-pass filter (LPF) based on spectra of atomic functions $${{{\text{h}}}_{a}}(x)$$ is first proposed.... 相似文献
8.
Shi Shuang Ma Yujunrong Ren Shunqing 《Multidimensional Systems and Signal Processing》2019,30(2):543-560
Multidimensional Systems and Signal Processing - This work is concerned with $$\mathscr {H}_{\infty }$$ filter design with missing measurements for a class of two-dimensional (2-D) switched systems... 相似文献
9.
Given the initial energy supplies and the maximal transmission power of the individual nodes in a wireless ad hoc network,
a power schedule of duration t for a specified topological property
is a scheduling of the transmission powers of the individual nodes over the period [0, t] such that (1) the total amount of energy consumed by each node during the period [0, t] does not exceed its initial energy supply, (2) the transmission power of each node at any moment in the period [0, t] does not exceed its maximal transmission power, and (3) the produced network topology at any moment in the period [0, t] satisfies the property
. The problem Max-Life Power Schedule for
seeks a power schedule of the maximal duration for
. Let g be the golden ratio
, and ε be an arbitrarily positive constant less than one. In this paper, we present a
-approximation algorithm for Max-Life Power Schedule for Connectivity, a
-approximation algorithm for Max-Life Power Schedule for 2-Node-Connectivity, and a
-approximation algorithm for Max-Life Power Schedule for 2-Edge-Connectivity.
This work is supported in part by Research Grants Council of Hong Kong under grant number CityU 9041040.
Peng-Jun Wan received his Ph.D. degree from University of Minnesota, MS degree from The Chinese Academy of Science, and BS degree from
Tsinghua University. He is currently an Associate Professor in Computer Science at Illinois Institute of Technology, and at
City University of Hong Kong. His research interests include wireless networks, optical networks, and algorithm design and
analysis.
Chih-Wei Yi received his M.S. and B.S. degrees from National Taiwan University. He is currently a Ph.D. candidate at the Illinois Institute
of Technology. His dissertational research focuses on wireless ad hoc networks. He is expected to graduate in 2005. 相似文献
10.
S.M. Bishop C.L. Reynolds Jr. Z. Liliental-Weber Y. Uprety J. Zhu D. Wang M. Park J.C. Molstad D.E. Barnhardt A. Shrivastava T.S. Sudarshan R.F. Davis 《Journal of Electronic Materials》2007,36(4):285-296
The polytype and surface and defect microstructure of epitaxial layers grown on 4H(), 4H(0001) on-axis, 4H(0001) 8° off-axis, and 6H(0001) on-axis substrates have been investigated. High-resolution x-ray diffraction
(XRD) revealed the epitaxial layers on 4H() and 4H(0001) 8° off-axis to have the 4H-SiC (silicon carbide) polytype, while the 3C-SiC polytype was identified for epitaxial
layers on 4H(0001) and 6H(0001) on-axis substrates. Cathodoluminescence (CL), Raman spectroscopy, and transmission electron
microscopy (TEM) confirmed these results. The epitaxial surface of 4H() films was specular with a roughness of 0.16-nm root-mean-square (RMS), in contrast to the surfaces of the other epitaxial
layer-substrate orientations, which contained curvilinear boundaries, growth pits (∼3 × 104 cm−2), triangular defects >100 μm, and significant step bunching. Molten KOH etching revealed large defect densities within 4H() films that decreased with film thickness to ∼106 cm−2 at 2.5 μm, while cross-sectional TEM studies showed areas free of defects and an indistinguishable film-substrate interface for 4H() epitaxial layers. 相似文献
11.
C. André D. Vasilevskiy S. Turenne R. A. Masut 《Journal of Electronic Materials》2009,38(7):1061-1067
Thermoelectric (TE) generator modules for a number of waste heat recovery applications are required to operate between room
temperature and 500 K, a temperature range for which the composition of bismuth-telluride-based alloys needs to be adjusted
to optimize performance. In particular n-type alloys do not perform as well as p-type and require a more systematic study. We have produced, by mechanical alloying followed by hot extrusion, alloys, within the range with fixed carrier concentration () to optimize their TE performance in the temperature range 300 K to 420 K. The optimum composition has been identified to
be and which is very close to the composition that also maximizes the ratio of the electron mobility to the lattice component of
the thermal conductivity. The optimized alloy performance can be further increased by adjusting the carrier concentration. 相似文献
12.
Wireless Networks - For a positive integer k, a radio k-coloring of a simple connected graph G?=?(V(G), E(G)) is a mapping $$f:V(G) \to \{ 0,1,2, \ldots \}$$ such that $$|f(u) - \,f(v)|... 相似文献
13.
S.K. Chan S.K. Lok G. Wang Y. Cai N. Wang I.K. Sou 《Journal of Electronic Materials》2008,37(9):1344-1348
Nanotrenches are induced by thermal annealing Au droplets on ZnSe surfaces. High-resolution scanning electron microscopy studies
of the nanotrench structures reveal that the preferred migration directions of the catalyst droplets are along the direction family. On a ZnSe(111)B surface, each of the trenches is along one of the six directions while on a nonvicinal ZnSe(100) surface, the trenches are along a pair of antiparallel directions. Based on the results obtained from atomic force microscopy surface profiling and electron energy-loss spectroscopy
chemical analysis techniques, a model is proposed to describe the possible formation mechanisms of the␣observed nanotrenches.
The highly parallel nanotrenches induced on the Au/ZnSe(100) structure as revealed in this study are potentially useful as
a template for in situ fabrication of ordered one-dimensional nanostructures (such as nanowires) of many materials. 相似文献
14.
Wen Meng Tang Yuchao Cui Angang Peng Jigen 《Multidimensional Systems and Signal Processing》2019,30(3):1531-1544
Multidimensional Systems and Signal Processing - In this paper, we propose a new primal–dual fixed point algorithm with dynamic stepsize ( $$\hbox {PDFP}^{2}O_{DS_{n}}$$ ) for solving convex... 相似文献
15.
Kenji Monden 《Journal of Electronic Materials》2007,36(12):1691-1696
The creep properties of tin-based, lead-free solders, Sn-3.0Ag-0.5Cu and Sn-7.5Zn-3.0Bi, were investigated for the temperature
range from 298 K to 398 K. The creep rupture time decreases with increasing initial stress and temperature. The Omega method
is applied to the analysis of the solder creep curves. The creep rate is expressed by the following formula: , where and Ω are experimentally determined. The parameter , the imaginary initial strain rate, increases with increasing initial stress and temperature. The parameter Ω is temperature dependent, but less dependent on the initial stress. The apparent activation energy for is 108 kJ/mol in Sn-3.0Ag-0.5Cu and 83 kJ/mol in Sn-7.5Zn-3.0Bi. These values are close to the activation energy for the
lattice diffusion of tin. The creep rupture time is calculated using the parameters and Ω. The calculated creep rupture time is in good agreement with the measured creep rupture time. 相似文献
16.
Ohmic contacts to n-type 4H- and 6H-SiC without postdeposition annealing were achieved using an interlayer of epitaxial InN beneath a layer of
Ti. The InN films were grown by reactive dc magnetron sputtering at 450°C, whereas the Ti films were deposited by electron-beam
evaporation at room temperature. The InN films were characterized by x-ray diffraction (XRD), secondary electron microscopy
(SEM), cross-sectional transmission electron microscopy (TEM), and Hall-effect measurements. Both XRD and TEM observations
revealed that the Ti and InN films have epitaxial relationships with the 6H-SiC substrate as follows: (0001)[]Ti∥(0001)[]InN∥(0001)[]6H-SiC. The Ti/InN/SiC contacts displayed ohmic behavior, whereas Ti/SiC contacts (without an InN interlayer) were nonohmic. These
results suggest that InN reduces the Schottky barrier height at the SiC surface via a small conduction-band offset and support previous reports of an electron accumulation layer at the surface of InN. 相似文献
17.
Hongyu Peng Tuerxun Ailihumaer Balaji Raghothamachar Michael Dudley 《Journal of Electronic Materials》2020,49(6):3472-3480
In x-ray topography studies, ray tracing simulation has been particularly useful in identifying and characterizing Burgers vectors of dislocations using only one reflection instead of the traditional method of recording at least three reflections and applying $$\vec{g} \cdot \vec{b} = 0$$ and $$\vec{g} \cdot \vec{b} \times \vec{l} = 0$$ criteria. In this study, ray tracing simulation of expected dislocations in (AlxGa(1–x))0.5In0.5P epitaxial layers on GaAs substrates has been carried out by using well-known expressions for displacement fields around dislocations. By comparing the simulated images with observed images on monochromatic x-ray topographs, the Burgers vectors have been characterized. The x-ray topographs from the (AlxGa(1–x))0.5In0.5P epitaxial layers also reveal a unique pattern consisting of a series of circular dark contrast features from inclusions. These dark circles decrease in size as the center of the inclusions is approached. Ray tracing simulated image of an inclusion assuming a spherical strain field matches well with the experimental image, thus providing information on the level of strain around the inclusion. 相似文献
18.
Sushkov A. A. Pavlov D. A. Shengurov V. G. Denisov S. A. Chalkov V. Yu. Baidus N. V. Rykov A. V. Kryukov R. N. 《Semiconductors》2019,53(9):1242-1245
Semiconductors - A GaAs/AlAs/GaAs/AlAs/Ge heterostructure grown on a Si/Al2O3(1 $$\bar {1}$$ 02) substrate is formed and studied. The Ge buffer layer is produced by the “hot wire”... 相似文献
19.
The ultraviolet (UV) photoelectric characteristics of transitional metal (Cu) doped ZnO nanowires produced by the self-catalytic
vapor–liquid–solid (VLS) method were investigated by performing a series of photoconduction and time-resolved measurements.
The photocurrent voltage characteristics obtained on the nanowires configured as two-terminal metal–semiconductor–metal photodetectors
exhibited a nonmonotonic behavior attributed to the interplay of several limiting mechanisms: Schottky contacts and trapping/detrapping
effects that take place at low and intermediate (pre-avalanche) bias regimes, respectively. In the intermediate biases, the
photocurrent was power-law dependent, i.e., changed with voltage as
and for excitation wavelengths of 365 nm, 302 nm, and 254 nm, respectively. The dependence of the exponent on the wavelength
of the light is analyzed and explained based on the detailed consideration of the contribution of different deep-defect Cu
levels formed within the band gap of ZnO. The study will be important to those working in the area of ZnO-based nanophotodetectors,
optical switches, and sensors. 相似文献
20.
Sarker Dilip Kumar Sarkar Md. Zahurul Islam Anower Md. Shamim Sultana Rezwana 《International Journal of Wireless Information Networks》2022,29(3):303-313
International Journal of Wireless Information Networks - This paper exhibits the confidentiality performance study of a cooperative multicast network consisting of $${\mathcal {K}}$$ asymmetric... 相似文献