1,738,810 research outputs found
fhxu00/MBE-GPU: v1.0.0
No full textThis is the artifacts of paper "Efficient Maximal Biclique Enumeration on GPUs", which will appear in SC'23.
Abstract:
Maximal biclique enumeration (MBE) in bipartite graphs is an important problem in data mining with many real-world applications. All existing solutions for MBE are designed for CPUs. Parallel MBE algorithms for GPUs are needed for MBE acceleration leveraging its many computing cores. However, enumerating maximal bicliques using GPUs has three main challenges including large memory requirement, thread divergence, and load imbalance. In this paper, we propose GMBE, the first highly-efficient GPU solution for the MBE problem. To overcome the challenges, we design a stack-based iteration approach to reduce GPU memory usage, a pro-active pruning method using the vertex's local neighborhood size to alleviate thread divergence, and a load-aware task scheduling framework to achieve load balance among threads within GPU warps and blocks. Our experimental results show that GMBE on an NVIDIA A100 GPU can achieve 70.6x speedup over the state-of-the-art parallel MBE algorithm PARMBE on a 96-core CPU machine
Customized nanostructures MBE growth: from quantum dots to quantum rings
No full text2 páginas, 2 figuras.-- Comunicación oral presentada a la XII International Conference on Molecular Beam Epitaxy, MBE-XII celebrada en San Francisco (EE.UU.) del 15 al 20 de Septiembre de 2002.Studies for growing control methods of quantum dots (QD) sizes and dot/cap intermixing for tuning QD optical properties have particular interest nowadays. Morphological shape surface changes of QD due to thin capping overgrowth of GaAs under different growing conditions has been reported by different authors [1, 2] as a powerful technique to obtain different nanostructures. In this work, control over shape and optical emission of molecular beam epitaxy (MBE) thin capping overgrown InAs QD on GaAs[100] have been studied, using ex-situ Atomic Force Microscopy (AFM) and Photoluminescence (PL).Peer reviewe
Characterisation of InAs/GaAs short period superlattices using column ratio mapping in aberration-corrected scanning transmission electron microscopy
Get PDFThe image processing technique of columnratiomapping was applied to aberration-corrected high angle annular dark field (HAADF) images of shortperiod MBE (molecular beam epitaxy) grown InAs/GaAssuperlattices. This method allowed the Indium distribution to be mapped and a more detailed assessment of interfacial quality to be made. Frozen-phonon multislice simulations were also employed to provide a better understanding of the experimental columnratio values. It was established that ultra-thin InAs/GaAs layers can be grown sufficiently well by MBE. This is despite the fact that the Indium segregated over 3–4 monolayers. Furthermore, the effect of the growth temperature on the quality of the layers was also investigated. It was demonstrated that the higher growth temperature resulted in a better quality superlattice structure
MBE-grown 232-270nm deep-UV LEDs using monolayer thin binary GaN/AlN quantum heterostructures
No full textMBE-grown 232-270nm deep-UV LEDs using monolayer thin binary GaN/AlN quantum heterostructure
MBE for Services to the Arts
Get PDFRoselind Sinclair, Lecturer in Design Education , awarded an MBE for Services to the Arts in the Kings 2024, New Years Honours List.
Roselind was presented with her award at Windsor Castle by Anne, The Princess Royal on Wednesday March 6th , 202
Feststoffquellen-MBE-Wachstum von InP-basierenden DHBT > für schnelle Datenkommunikationsanwendungen
No full textS.1001-1004We report on the development of a double heterojunction bipolar transistor (DHBT) technology on InP substrates for high-speed data communication. The technology is based on DHBTs with an InP emitter, a graded InGaAs:C base and a composite InGaAs/InGaAsP/InP collector, grown by solid source phosphorous MBE. High carbon doping levels in the base layer with excellent carrier mobility values allow the fabrication of devices with DC current gain about 90 and cut-off frequencies beyond f(ind t)=265 GHz. Using this technology, integrated circuits, including lumped amplifiers, voltage controlled oscillators, multiplexers and demultiplexers, suitable for operation at 40 and 80 Gbit/s have been successfully fabricated
Growth and Characterisation of GaAsBi
Get PDFThis thesis reports the optical and structural properties of GaAs(1-x)Bi(x) alloys grown on GaAs by Molecular Beam Epitaxy (MBE). The photoluminescence (PL) of a GaAs(0.97)Bi(0.03) alloy was measured over a wide range of temperatures and excitation powers. The temperature dependence of the PL peak energy indicated significant exciton localization at low temperatures and the band gap varies more weakly with temperature than in GaAs. An analysis of dominant carrier recombination mechanism(s) was also carried out indicating that radiative recombination is dominant at low temperature.
The PL results indicate that dilute fractions of bismuth (Bi) with x < 0.025 improve the material quality of these low temperature growth alloys by reducing the density of gallium (Ga) and/or arsenic related defects. The crystal quality starts to degrade at higher Bi concentration probably due to a significant amount of Bi-related defects, i.e BiGa. However, the room temperature PL intensity continues to increase with Bi content for x up to 0.06 due to the greater band-gap offset between GaAs and GaAs(1-x)Bi(x).
To improve the quality of GaAs(1-x)Bi(x) alloys, annealing and growth studies were carried out. At room temperature, the annealed GaAs(1-x)Bi(x) showed a modest improvement (~ 3 times) in PL while the PL peak wavelength remained relatively unchanged. Also, the optimum annealing temperature is Bi composition dependent; for samples with x < 0.048, the optimum annealing temperature is 700 oC but it reduces to 600 oC for higher compositions.
Two growth parameters were investigated which are growth rate and As4/Bi beam equivalent pressure (BEP) ratio. It was found that growth rate significantly affects Bi incorporation and the accumulation of surface Bi. Decreasing the As4/Bi BEP ratio has been shown to increase Bi concentration but is limited by the formation of Bi double PL peaks
Sub-micron, Metal Gate, High-к Dielectric, Implant-free, Enhancement-mode III-V MOSFETs
Get PDFThe performance of 300nm, 500nm and 1μm metal gate, implant free, enhancement mode III-V MOSFETs are reported. Devices are realised using a 10nm MBE grown Ga2O3/(GaxGd1-x)2O3 high-κ (κ=20) dielectric stack grown upon a δ-doped AlGaAs/InGaAs/AlGaAs/GaAs heterostructure. Enhancement mode operation is maintained across the three reported gate lengths with a reduction in threshold voltage from 0.26 V to 0.08 V as the gate dimension is reduced from 1 μm to 300 nm. An increase in transconductance is also observed with reduced gate dimension. Maximum drain current of 420 μA/μm and extrinsic transconductance of 400 µS/µm are obtained from these devices. Gate leakage current of less than 100pA and subthreshold slope of 90 mV/decade were obtained for all gate lengths. These are believed to be the highest performance submicron enhancement mode III-V MOSFETs reported to date
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