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Three-dimensional structured on-chip stacked zone plates for nanoscale X-ray imaging with high efficiency

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Nano Research 2014年第4期7卷 528-535页

作者： Stephan Werner Stefan Rehbein peter guttmann Gerd Schneider Helmholtz-Zentrum Berlin fur Materialien und Energie GmbH Institute for Soft Matter and Functional Materials Albert-Einstein-Straβe15 12489 Berlin Germany

Fresnel zone plates are the key optical elements for nanoscale focusing of X-ray beams with high spatial resolution. Conventional zone plates manufactured by planar nanotechnology processes are limited by the achievable aspect ratios of their zone structures. Additionally, ultra-high resolution X-ray optics with high efficiency requires three-dimensional （3-D） shaped tilted zones. The combination of high spatial resolution and high diffraction efficiency is a fundamental problem in X-ray optics. Based on electrodynamical simulations, we find that the optimized zone plate profile for volume diffraction is given by zone structures with radially increasing tilt angles and decreasing zone heights. On-chip stacking permits the realization of such advanced 3-D profiles without significant loss of the maximum theoretical efficiency. We developed triple layer on-chip stacked zone plates with an overlay accuracy of sub-2 nm which fulfills the nanofabrication requirements. Efficiency measurements of on-chip stacked zone plates show significantly increased values compared to conventional zone plates.

关键词： X-ray optics Fresnel zone plates X-ray imaging X-ray microscopy volume diffraction

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软X射线显微术和光谱显微术(英文)

光学精密工程 2007年第12期15卷 1878-1885页

作者： J Thieme S Gleber G Mitrea p.guttmann Institute for X-ray physics Friedrich-Hund-Platz 1D-37077 GttingenGermany Institute for X-ray physics c/o BESSY GmbHAlbert-Einstein-Strasse 15D-12489 BerlinGermany

X射线显微术可直接在水环境中对胶体颗粒尺寸范围内的颗粒进行高分辨率成像,将该项技术与高分辨率光谱相结合,还可用于光谱显微研究。其中,常用的两种X射线显微镜是透射显微镜和扫描透射显微镜,文中示出了它们的装置图。由于X射线显微... 详细信息

X射线显微术可直接在水环境中对胶体颗粒尺寸范围内的颗粒进行高分辨率成像,将该项技术与高分辨率光谱相结合,还可用于光谱显微研究。其中,常用的两种X射线显微镜是透射显微镜和扫描透射显微镜,文中示出了它们的装置图。由于X射线显微镜能迅速拍下一物体的高分辨率图像,所以,作为一种分析仪器,扫描X射线显微镜更适合作光谱显微研究。作为形态学目视化的一个示例,本文用一台透射X射线显微镜拍摄了粘土和土壤样品的图像。根据X射线图像进行的低温层析实验所获得的图像得到了有关细菌构成的显微生存环境以及其它土壤胶状体的3D结构信息。对扫描透射X射线显微镜拍摄的一系列图像进行分析,得到了土壤样品的形貌特性和化学特性。

关键词： X射线显微木光谱显微木 XANES NEXAFS 环境科学胶体颗粒

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

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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

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

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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

Alveolar stability under different combinations of positive end-expiratory pressure and tidal volume： alveolar microscopy in isolated injured rat lungs

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Chinese Medical Journal 2010年第4期123卷 406-411页

作者： LIU Hui Claudius A. Stahl Knut Moeller Matthias Schneider Steven Ganzert ZHAO Zhan-qi TONG Xiao-wen Josef guttmann Department of Breast Surgery Tongji Hospital Tongji University School of Medicine Shanghai 200065 China Department of Anesthesiology and Critical Care Medicine University Medical Center Freiburg 79106 Germany Biomedical Engineering Furtwangen University VS-Schwenningen 78056 Germany Woman Health Care Center of Tongji University Shanghai 200065 China

Background High positive end-expiratory pressure （pEEp） and low tidal volume （VT） ventilation is thought to be a protective ventilation strategy. It is hypothesized that the stabilization of collapsible alveoli during expiration contributes to lung protection. However, this hypothesis came from analysis of indirect indices like the analysis of the pressure-volume curve of the lung. The purpose of this study was to investigate isolated healthy and injured rat lungs by means of alveolar microscopy, in which combination of pEEp and VT is beneficial with respect to alveolar stability （I-E%）. Methods Alveolar stability was investigated in isolated, non-perfused mechanically ventilated rat lungs. Injured lungs were compared with normal lungs. For both groups three pEEp settings （5, 10, 20 cmH20） were combined with three VT settings （6, 10, 15 ml/kg） resulting in nine pEEp-VT combinations per group. Analysis was performed by alveolar microscopy. Results In normal lungs alveolar stability persisted in all pEEp-VT combinations （I-E% （3.2±11.0）%）. There was no significant difference using different settings （p 〉0.01）. In contrast, alveoli in injured lungs were extremely instable at pEEp levels of 5 cmH20 （mean I-E% 100%） and 10 cmH2O （mean I-E% （30.7±16.8）%）; only at a pEEp of 20 cmH20 were alveoli stabilized （mean I-E% of （0.2±9.3）%）. Conclusions In isolated healthy lungs alveolar stability is almost unaffected by different settings of pEEp and VT. In isolated injured lungs only a high pEEp level of 20 cmH2O resulted in stabilized alveoli whereas lower pEEp levels are associated with alveolar instability.

关键词： alveolar microscopy alveolar mechanics tidal volume positive end-expiratory pressure

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

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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

Improved performance of UVC-LEDs by combination of high-temperature annealing and epitaxially laterally overgrown AlN/sapphire

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photonics Research 2020年第4期8卷 589-594页

作者： NORMAN SUSILO EVIATHAR ZIFFER SYLVIA HAGEDORN LEONARDO CANCELLARA CARSTEN NETZEL NEYSHA LOBO pLOCH SHAOJUN WU JENS RASS SEBASTIAN WALDE LUCA SULMONI MARTIN guttmann TIM WERNICKE MARTIN ALBRECHT MARKUS WEYERS MICHAEL KNEISSL Institute of Solid State physics Technische Universitat BerlinHardenbergstraβe 3610623 BerlinGermany Ferdinand-Braun-Institut Leibniz-Institut für HochstfrequenztechnikGustav-Kirchhoff-Strafβe 412489 BerlinGermany Leibniz-Institut für Kristallzüchtung Max-Born-Strafβe 212489 BerlinGermany

We report on the performance of AlGaN-based deep ultraviolet light-emitting diodes(UV-LEDs)emitting at 265 nm grown on stripe-patterned high-temperature annealed(HTA)epitaxially laterally overgrown(ELO)aluminium nitride(AIN)/sapphire *** this purpose,the structural and electro-optical properties of ultraviolet-c light-emitting diodes(UVC-LEDs)on as-grown and on HTA planar AlN/sapphire as well as ELO AlN/sapphire with and without HTA are investigated and *** measurements reveal dark spot densities of 3.5×10^9 cm^-2,1.1×10^9 cm^-2,1.4×10^9 cm^-2,and 0.9×10^9 cm^-2 in multiple quantum well samples on as-grown planar AIN/sapphire,HTA planar AlN/sapphire,ELO AlN/sapphire,and HTA ELO AlN/sapphire,respectively,and are consistent with the threading dislocation densities determined by transmission electron microscopy(TEM)and high-resolution X-ray diffraction rocking *** UVC-LED performance improves with the reduction of the threading dislocation densities(TDDs).The output powers(measured on-wafer in cw operation at 20 mA)of the UV-LEDs emitting at 265 nm were 0.03 mW(planar AlN/sapphire),0.8 mW(planar HTA AlN/sapphire),0.9 mW(ELO AlN/sapphire),and 1.1 mW(HTA ELO AlN/sapphire),***,Monte Carlo ray-tracing simulations showed a 15%increase in light-extraction efficiency due to the voids formed in the ELO *** results demonstrate that HTA ELO AlN/sapphire templates provide a viable approach to increase the efficiency of UV-LEDs,improving both the internal quantum efficiency and the light-extraction efficiency.

关键词： Improved performance UVC-LEDs combination high-temperature annealing epitaxially laterally overgrown AlN/sapphire AlN UVC

MOVpE-grown AlGaN-based tunnel heterojunctions enabling fully transparent UVC LEDs

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photonics Research 2019年第5期7卷 I0008-I0012页

作者： Christian Kuhn Luca Sulmoni Martin guttmann Johannes Glaab Norman Susilo Tim Wernicke Markus Weyers Michael Kneissl Technische Universitat Berlin Institute of Solid State Physics Hardenbergstr. 36 EW6-1 10623 Berlin Germany Ferdinand-Braun-Institut Leibniz-Institut fur Hochstfrequenztechnik Gustav-Kirchhoff-Str. 4 12489 Berlin Germany

We report on AlGaN-based tunnel heterojunctions grown by metalorganic vapor phase epitaxy enabling fully transparent UVC LEDs by eliminating the absorbing p-AlGaN and p-GaN layers. Furthermore, the electrical characteristics can be improved by exploiting the higher conductivity of n-AlGaN layers as well as a lower resistance of n-contacts. UVC LEDs with AlGaN:Mg/AlGaN:Si tunnel junctions exhibiting single peak emission at268 nm have been realized, demonstrating effective carrier injection into the AlGaN multiple quantum well active region. The incorporation of a low band gap interlayer enables effective tunneling and strong voltage ***, the interlayer thickness is systematically varied. Tunnel heterojunction LEDs with an 8 nm thick GaN interlayer exhibit continuous-wave emission powers >3 m W near thermal rollover. External quantum efficiencies of 1.4% at a DC current of 5 m A and operating voltages of 20 V are measured on-wafer. Laterally homogeneous emission is demonstrated by UV-sensitive electroluminescence microscopy images. The complete UVC LED heterostructure is grown in a single epitaxy process including in situ activation of the magnesium acceptors.

关键词： MOVpE-grown AlGaN-based UVC LEDs

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单克隆抗体在肾移植方面的应用

国外医学情报 1982年第17期 289-289页

作者： R D guttmann 加拿大麦吉尔大学皇家维多利亚医院肾移植中心主任及教授

单克隆抗体已成为免疫学最重要的技术,在目前和不久的将来会有很多单克隆抗体应用于移植,既可用于诊断,也可用于治疗。这项新技术是从1979年开始的。所有淋巴细胞原始是由骨髓产生,有一些淋巴细胞到胸腺而变成T淋巴细胞。T淋巴细胞有三... 详细信息

单克隆抗体已成为免疫学最重要的技术,在目前和不久的将来会有很多单克隆抗体应用于移植,既可用于诊断,也可用于治疗。这项新技术是从1979年开始的。所有淋巴细胞原始是由骨髓产生,有一些淋巴细胞到胸腺而变成T淋巴细胞。T淋巴细胞有三种亚型,即辅助T淋巴细胞、抑制T淋巴细胞和杀伤T淋巴细胞。另外免疫系统还有B淋巴细胞系统,也由骨髓产生,但不到胸腺,这些B淋巴细胞转化成能产生各种抗体的浆细胞。辅助细胞可引起B细胞产生更多的抗体,而抑制细胞使B细胞产生的抗体减少,所以辅助细胞和抑制细胞成为调节系统,在B细胞产

关键词：单克隆抗体辅助细胞细胞抗体