检索结果-南通市图书馆

Petroleum Science 2024年第3期21卷 1683-1698页

作者： Bogdan Sebacher Remus Hanea Department of Applied Informatics Military Technical Academy“Ferdinand I”Bucharest 050141Romania Equinor Sandslivegen 905254 SandsliBergenNorway

The facies distribution of a reservoir is one of the biggest concerns for geologists,geophysicists,reservoir modelers,and reservoir engineers due to its high importance in the setting of any reliable decisionmaking/optimization of field development *** approach for parameterizing the facies distribution as a random variable comes naturally through using the probability *** the prior probability fields of facies come either from a seismic inversion or from other sources of geologic information,they are not conditioned to the data observed from the cores extracted from the *** paper presents a regularized element-free Galerkin(R-EFG)method for conditioning facies probability fields to facies *** conditioned probability fields respect all the conditions of the probability theory(*** the values are between 0 and 1,and the sum of all fields is a uniform field of 1).This property achieves by an optimization procedure under equality and inequality constraints with the gradient projection *** conditioned probability fields are further used as the input in the adaptive pluri-Gaussian simulation(APS)methodology and coupled with the ensemble smoother with multiple data assimilation(ES-MDA)for estimation and uncertainty quantification of the facies *** history-matching of the facies models shows a good estimation and uncertainty quantification of facies distribution,a good data match and prediction capabilities.

关键词： Element free Galerkin(EFG) Adaptive pluri-Gaussian simulation(APS) Facies distribution estimation Ensemble smoother with multipledata assimilation(ESMDA)

High duty cycle,highly efficient fiber coupled 940-nm pump module for high-energy solid-state lasers

在线全文

学校读者我要写书评

暂无评论

High Power Laser Science and Engineering 2016年第1期4卷 17-21页

作者： Ren Platz Bernd Eppich Juliane Rieprich Wolfgang Pittroff Gtz Erbert Paul Crump ferdinand-braun-Institut Leibniz-Institut fr Hchstfrequenztechnik

Tailored diode laser single emitters with long(6 mm) resonators and wide(1.2 mm) emission apertures that operate with940 nm emission wavelength were assembled in novel edge-cooled vertically stacked arrays, and used to construct a compact and highly efficient fiber coupled pump source for Yb:YAG pulsed high-energy class solid-state lasers. The novel configuration is shown to allow repetition rates of 200 Hz at 1 ms pulse duration, at an output power of 130 W per single emitter. The emission of two stacked arrays was then optically combined to realize pump modules that deliver6 kW peak power(pulse energy 6 J) from a 1.9 mm core diameter fiber, with wall plug efficiency of 50%. This represents a significant improvement in terms of duty cycle and electro-optical efficiency over conventional sources. The pump module has been successfully tested at the Max Born Institute, Berlin during trials for pumping of disk lasers.

关键词： diode laser diode pumped solid-state laser fiber coupling high-power QCW diode laser stack

Diameter evolution of selective area grown Ga-assisted GaAs nanowires

在线全文

学校读者我要写书评

暂无评论

Nano Research 2018年第5期11卷 2885-2893页

作者： Hanno Kupers Ryan B. Lewis Abbes Tahraoui Mathias Matalla Olaf Kruger Faebian Bastiman Henning Riechert Lutz Geelhaar Paul-Drude-Institut fur Festkorperelektronik Hausvogteiplatz 5-7 10117 Berlin Germany ferdinand-braun-Institut Leibniz-Institut fur Hochstfrequenztechnik Gustav-Kirchhoff-Strasse 4 12489 Berlin Germany

Tapering of vapour-liquid-solid （VLS） grown nanowires （NWs） is a widespread phenomenon resulting from dynamics of the liquid droplet during growth and direct vapour-solid （VS） growth on the sidewall. To investigate both effects in a highly controlled wa35 we developed a novel two-step growth approach for the selective area growth （SAG） of GaAs nanowires （NWs） by molecular beam epitaxy. In this growth approach optimum growth parameters are provided for the nucleation of NWs in a first step and for the shape variation during elongation in a second step, allowing NWs with a thin diameter （45 nrn） and an untapered morphology to be realized with high vertical yield. We quantify the flux dependence of radial VS growth and build a model that takes into account diffusion on the NW sidewalls to explain the observed VS growth rates. As our model is consistent with axial VLS growth we can combine it with an existing model for the diameter variation due to the droplet dynamics at the NW top. Thereby, we achieve full understanding of the diameter of NWs over their entire length and the evolution of the diameter and tapering during growth. We conclude that only the combination of droplet dynamics and VS growth results in an untapered morphology. This result enables NW shape engineering and has important implications for doping of NWs.

关键词： GaAs molecular beam epitaxy semiconductor growth model nanowire tapering

Continuous-wave operation of 405 nm distributed Bragg reflector laser diodes based on GaN using 10th-order surface gratings

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Photonics Research 2022年第5期10卷 1157-1161页

作者： J.H.KANG H.WENZEL E.FREIER V.HOFFMANN J.FRICKE O.BROX M.MATALLA S.EINFELDT ferdinand-braun-Institut gGmbH Leibniz-Institut für Höchstfrequenztechnik12489 BerlinGermany

Single longitudinal mode continuous-wave operation of GaN-based distributed Bragg reflector(DBR) laser diodes with 10 th-order surface gratings is demonstrated. The DBR consists of periodic V-shaped grooves on a 2 μm wide ridge waveguide fabricated by using electron-beam lithography and plasma etching. The effect of different lengths of the DBR section and the gain section on the device performance has been studied. Periodic mode hops to the adjacent longitudinal Fabry–Perot resonator mode at shorter wavelength have been observed when increasing the operation current. Between the mode hops, single longitudinal mode emission at around 405 nm is achieved with a full width at half-maximum of 0.03 nm. A linear redshift of the emission wavelength with increasing temperature of 0.019 nm/K was derived.

关键词： diodes waveguide resonator

在线全文

学校读者我要写书评

暂无评论

高压、快速开关GaN功率晶体管的技术途径

功能材料与器件学报 2013年第6期19卷 289-294页

作者： J.Würfl O.Hilt E.Bahat-Treidel R.Zhytnytska K.Klein P.Kotara F.Brunner A.Knauer O.Krüger M.Weyers G.Trnkle ferdinand-braun-Institut Leibniz Institut für Hchstfrequenztechnik

本文主要讨论用于功率电子电路中的快速开关GaN器件的技术途径。首先,概述对于在SiC和Si衬底上生长的器件,用于提高击穿电压的最先进技术。然后将这些技术与不同偏压下的动态开关特性联系起来。动态开关特性仍然落后于类似的竞争器件,... 详细信息

本文主要讨论用于功率电子电路中的快速开关GaN器件的技术途径。首先,概述对于在SiC和Si衬底上生长的器件,用于提高击穿电压的最先进技术。然后将这些技术与不同偏压下的动态开关特性联系起来。动态开关特性仍然落后于类似的竞争器件,尤其是如果考虑高偏压的开关特性时。开关特性一般用所谓的动态导通电阻表示。它与一些工艺参数的关系极大,这些参数如外延层的设计、缓冲层晶体品质、钝化层,最后,但并不是不重要的是横向器件设计(如场电极的布置)。说明了所有这些影响因素之间的平衡,及其与GaN高压开关器件现状的关系。

关键词：缓冲层击穿电压导通电阻开关特性击穿强度栅极漏电流功率器件动态掺杂高压开关

Recombination mechanisms and thermal droop in AlGaN-based UV-B LEDs

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2017年第2期5卷 44-51页

作者： CARLO DE SANTI MATTEO MENEGHINI DESIREE MONTI JOHANNES GLAAB MARTIN GUTTMANN JENS RASS SVEN EINFELDT FRANK MEHNKE JOHANNES ENSLIN TIM WERNICKE MICHAEL KNEISSL GAUDENZIO MENEGHESSO ENRICO ZANONI Department of Information Engineering University of Padova ferdinand-braun-Institut Leibniz-Institut fur Hochstfrequenztechnik Technische Universitat Berlin Institut für Festkorperphysik

This paper reports a comprehensive analysis of the origin of the electroluminescence(EL)peaks and of the thermal droop in UV-B AlGaN-based *** carrying out spectral measurements at several temperatures and currents,(i)we extract information on the physical origin of the various spectral bands,and(ii) we develop a novel closed-form model based on the Shockley–Read–Hall theory and on the ABC rate equation that is able to reproduce the experimental data on thermal droop caused by non-radiative recombination through deep *** the samples under test,the three EL bands are ascribed to the following processes:band-to-band recombination in the quantum wells(main EL peak),a parasitic intra-bandgap radiative transition in the quantum well barriers,and a second defect-related radiative process in the p-AlGaN superlattice.

关键词： Recombination mechanisms and thermal droop in AlGaN-based UV-B LEDs Ga AlGaN EBL SRH UV

400 μm stripe lasers for high-power fiber coupled pump modules

在线全文

学校读者我要写书评

暂无评论

High Power Laser Science and Engineering 2013年第1期1卷 60-67页

作者： Ren Platz Gtz Erbert Wolfgang Pittroff Moritz Malchus Klaus Vogel Gnther Trnkle ferdinand-braun-Institut Leibniz-Institut fr Hchstfrequenztechnik Gustav-Kirchhoff-Stra e 412489 BerlinGermany University of Applied Sciences Munich Lothstra e 34 80335 MunichGermany

We present a 940 nm quasi-continuous wave semiconductor laser designed as a building block for high-power fiber coupled pump *** laser comprises a 400μm narrow-stripe array mounted on an aluminum nitride substrate using hard *** chip has been optimized for high optical power and low lateral far-field *** vertical and six lateral structure variations have been investigated to determine the best achievable *** at 1 ms pulse width and a repetition rate of 10 Hz,the laser device reaches a maximum pulse power of 86 W from a 400μm aperture and more than 62%maximum conversion *** lateral far-field angles(95%power enclosed)of11.5 and 13.5,depending on the epitaxial design,enable efficient multimode fiber *** potential for highly reliable applications has been demonstrated.

关键词： diode laser high-power laser array optical fiber coupling

Electrical properties and microstructure formation of V/Al-based n-contacts on high Al mole fraction n-AlGaN layers

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2020年第8期8卷 1381-1387页

作者： LUCA SULMONI FRANK MEHNKE ANNA MOGILATENKO MARTIN GUTTMANN TIM WERNICKE MICHAEL KNEISSL Institut für Festkorperphysik Technische Universitat Berlin10623 BerlinGermany ferdinand-braun-Institut Leibniz-Institut fur Höchstfrequenztechnik12489 BerlinGermany Institut für Physik Humboldt Universität zu Berlin12489 BerlinGermany

The electrical and structural properties of V/Al-based n-contacts on n‐AlxGa1−xN with an Al mole fraction x ranging from x=0.75 to x=0.95 are *** n-contacts are obtained up to x=0.75 with a contact resistivity of 5.7×10^−4Ω·cm^2 whereas for higher Al mole fraction the IV characteristics are *** electron microscopy reveals a thin crystalline AlN layer formed at the metal/semiconductor interface upon thermal *** analysis confirmed an Al enrichment at the *** interfacial nitride-based layer in n-contacts on n‐Al0.9Ga0.1N is partly amorphous and heavily contaminated by *** role and resulting limitations of Al in the metal stack for n-contacts on n-AlGaN with very high Al mole fraction are ***,ultraviolet C(UVC)LEDs grown on n‐Al0.87Ga0.13N and emitting at 232 nm are fabricated with an operating voltage of 7.3 V and an emission power of 120μW at 20 mA in cw operation.

关键词： AlGaN fraction properties

Current-induced degradation and lifetime prediction of 310 nm ultraviolet light-emitting diodes

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2019年第7期7卷 14-18页

作者： Jan Ruschel Johannes Glaab Batoul Beidoun Neysha Lobo Ploch Jens Rass Tim Kolbe Arne Knauer Markus Weyers Sven Einfeldt Michael Kneissl ferdinand-braun-Institut Leibniz-Institut fur HochstfrequenztechnikGustav-Kirchhoff-Str.412489 BerlinGermany Technische Universitat Berlin Institut fur FestkorperphysikHardenbergstr.36EW6-710623 BerlinGermany

The impact of operation current on the degradation behavior of 310 nm UV LEDs is investigated over 1000 h of stress. It ranges from 50 to 300 mA and corresponds to current densities from 34 to 201 A/cm^*** separate the impact of current from that of temperature, the junction temperature is kept constant by adjusting the heat sink temperature. Higher current was found to strongly accelerate the optical power reduction during operation. A mathematical model for lifetime prediction is *** indicates that lifetime is inversely proportional to the cube of the current density, suggesting the involvement of Auger recombinati on.

关键词： degradation light-emitting diodes lifetime

Electrical and optical characteristics of highly transparent MOVPE-grown AlGaN-based tunnel heterojunction LEDs emitting at 232 nm

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2021年第6期9卷 1117-1123页

作者： FRANK MEHNKE CHRISTIAN KUHN MARTIN GUTTMANN LUCA SULMONI VERENA MONTAG JOHANNES GLAAB TIM WERNICKE MICHAEL KNEISSL Institute of Solid State Physics Technische Universität Berlin10623 BerlinGermany ferdinand-braun-Institut Leibniz-Institut für Höchstfrequenztechnik12489 BerlinGermany Current address:School of Electrical and Computer Engineering Georgia Institute of TechnologyAtlantaGeorgia 30332USA

We present the growth and electro-optical characteristics of highly transparent AlGaN-based tunnel heterojunction light-emitting diodes(LEDs)emitting at 232 nm entirely grown by metalorganic vapor phase epitaxy(MOVPE).A GaN:Si interlayer was embedded into a highly Mg-and Si-doped Al_(0.87)Ga_(0.13)N tunnel junction to enable polarization field enhanced *** LEDs exhibit an on-wafer integrated emission power of 77μWat 5 mA,which correlates to an external quantum efficiency(EQE)of 0.29%with 45μWemitted through the bottom sapphire substrate and 32μW emitted through the transparent top *** depositing a highly reflective aluminum reflector,a maximum emission power of 1.73 mW was achieved at 100 mA under pulsed mode operation with a maximum EQE of 0.35%as collected through the bottom substrate.

关键词： heterojunction MOVPE AlGaN