Sonia Gnanapragasam  Eberhard Richter  Frank Brunner  Andrea Denker  Richard Lossy  Michael Mai  Friedrich Lenk  Jörg Opitz-Coutureau  Gerhard Pensl  Jens Schmidt  Ute Zeimer  Liun Wang  Baskar Krishnan  Markus Weyers  Jaochim Würfl  Günther Tränkle 《Journal of Materials Science: Materials in Electronics》2008,19(1):64-67

AlGaN/GaN heterostructure field effect transistors (HFETs) were irradiated with protons as well as carbon, oxygen, iron and krypton ions of high (68 and 120 MeV) and low (2 MeV) energy with fluences in the range from 1 × 10⁷ to 1 × 10¹³ cm^?2. High energy irradiation with protons, carbon and oxygen produced no degradation in devices while krypton irradiation at the fluence of 1 × 10¹⁰ cm^?2 resulted in a small reduction of 2% in the transconductance. Similarly, for GaN samples irradiated with protons, carbon and oxygen at high energy no changes were seen by XRD, PL and Hall effect, while changes in lattice constant and a reduction in PL intensity were observed after irradiation with high energy krypton. Low energy irradiation with carbon and oxygen at a fluence of 5 × 10¹⁰ cm^?2 results in small change in the device performance while remarkable changes in device characteristics are seen at a fluence of 1 × 10¹² cm^?2 for carbon, oxygen, iron and krypton irradiation. Similarly changes are also observed by XRD, PL and Hall effect for the thick GaN layer irradiated at the fluence of 1 × 10¹² cm^?2. The device results and GaN layer properties are strongly correlated.  相似文献   

    

Yu Li Huang  Wei Chen  Hui Li  Jing Ma  Jens Pflaum  Andrew Thye Shen Wee 《Small (Weinheim an der Bergstrasse, Germany)》2010,6(1):70-75

A novel approach to constructing tunable and robust 2D binary molecular nanostructures on an inert graphite surface is presented. The guest molecules are embedded into a host molecular matrix and constrained via the formation of multiple intermolecular hydrogen bonds. By varying the binary molecular ratio and the molecular geometry, various molecular arrays with tunable intermolecular distances are fabricated. The results suggest a promising route for the fabrication of ordered and stable molecular nanostructure arrays for molecular sensors, molecular spintronic devices, and molecular p–n nanojunctions.  相似文献   

    

Jens‐Peter Heinß Dr. 《真空研究与实践》2007,19(5):20-23

Hydrogen free amorphous carbon coatings ‐ deposited with plasma‐activated high‐rate evaporation By using the technology of the plasmaactivated electron beam evaporation we deposited hydrogen free amorphous carbon coatings with deposition rates of up to 100 μm/h. The results of the mechanical and tribological investigations show the potential of these layers for the use in case of wear resistance. Hardnesses of up to 16GPa were proved. The actual state of the characterisation of the coatings is described and the outlook onto possibilities of further optimisation is given.  相似文献   

    

Jens Høyrup 《Centaurus; international magazine of the history of science and medicine》2011,53(3):248-251

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Francisco Fernández‐Trillo  Jan C. M. van Hest  Jens C. Thies  Thierry Michon  Ralf Weberskirch  Neil R. Cameron 《Advanced materials (Deerfield Beach, Fla.)》2009,21(1)

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Eva‐Kathrin Schillinger  Elena Mena‐Osteritz  Jens Hentschel  Hans G. Börner  Peter Bäuerle 《Advanced materials (Deerfield Beach, Fla.)》2009,21(16)

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  总被引：1，自引：0，他引：1  

Fredrik Eriksson  Naureen Ghafoor  Franz Schfers  Eric M. Gullikson  Jens Birch 《Thin solid films》2006,500(1-2):84-95

Low-energy ion-assisted magnetron sputter deposition has been used for the synthesis of highly reflective Ni/V multilayer soft X-ray mirrors. A low ion energy and a high ion-to-metal flux ratio were employed in order to stimulate the adatom mobility while minimizing ion-induced intermixing at the interfaces. An analytic model, based on the binary collision approximation, was used in order to gain insight into low-energy ion–surface interactions as a function of ion energy and ion-to-metal flux ratio. The model predicted a favorable region in the ion energy-flux parameter space where only surface atomic displacements are stimulated during growth of Ni and V for multilayers. For a series of Ni/V multilayer mirrors with multilayer periods about Λ = 1.2 nm, grown with a continuous ion assistance using energies in the range 7–36 eV and with ion-to-metal flux ratios Φ_Ni = 4.7 and Φ_V=20.9, specular and diffuse X-ray scattering analyses revealed that ion energies of 27–31 eV produced the best trade-off between reduced interfacial roughness and intermixing. However, it was also concluded that an interface mixing of about ± 1 atomic distance is unavoidable when a continuous flux of assisting ions is used.

To overcome this limitation, a sophisticated interface engineering technique was employed, where the first 0.3 nm of each layer was grown with a high-flux low-energy ion assistance and the remaining part was grown with a slightly higher ion energy. This method was demonstrated to largely eliminate the intermixing while maintaining the smoothening effect of ion assistance. Two Ni/V multilayer soft X-ray mirror structures, one with 500 periods designed for near-normal incidence and one 150 periods reflecting polarizer at the Brewster angle, were grown utilizing the interface engineering concept. Both the near-normal incidence reflectivity as well as polarizability were improved by a factor of 2 as compared to previously reported data for an X-ray energy of E = 511 eV.  相似文献   

    

Steffen Runkel  Oliver Hohn  Jens Degenhardt  Bjrn Roos 《真空研究与实践》2005,17(5):246-251

Applications of optical technologies like vision care, digital imaging or data communication play a decisive role in our daily life. Manipulation of light is mainly done using optical lenses. Beside mineral lenses, transparent plastic materials become more and more important. The optical and mechanical properties of lenses are crucially improved by high‐quality coatings. These includes primarily anti‐reflective coatings to enhance light transmission, hard coats to improve scratch resistance of the sensitive plastic substrates and finally clean coats to inhibit dusting of the lenses and to ease cleaning. In the following we present modern vacuum coating technologies for industrial refinement of optical substrates. The focal point is set to the coating of plastic eyeglass lenses using a revolutionary inline technology. On one hand the technology merges all coating steps in a fully automated system and enables on the other hand the flexible combination of different layer stacks necessary for RX‐production of ophthalmic lenses. This inline technology is available by the coating system OPTICUS. The design of the OPTICUS is described in the last chapter.  相似文献   

    

Wolfram Jger  Peter Schps  Jens Hoffmann  Gunar Beier  Torsten Pflücke 《Mauerwerk》2005,9(5):195-205

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Anna Medvedeva  Jens Bergström  Staffan Gunnarsson 《国际钢铁研究》2008,79(5):376-381

Combined effects of inclusions, surface condition and geometrical stress concentration on the fatigue strength of a tool steel have been studied. Bending fatigue testing was performed for milled tool components and smooth specimens produced from an experimental AISI H13 tool steel with varying additions of sulphur and oxygen. Inclusion distributions of the different test series were determined. Fracture surfaces after fatigue failures were studied in a scanning electron microscope. The sulphur content does not have a significant influence on the fatigue strength of the milled tool components in the range of 0.02 ‐ 0.09 wt%. A clear reduction in the fatigue strength is obtained for the smooth specimens when the steel becomes rich in inclusions. Here, the oxide type inclusions dominated as crack initiators and the effect of sulphides was smaller. The results demonstrate the reduced effect of inclusions on the fatigue strength in components with large stress concentrations and rough surfaces.  相似文献