Semiconductors

A semiconductor is a substance, usually a solid chemical element or compound, that can conduct electricity under some conditions but not others, making it a good medium for the control of electrical current. Its conductance varies depending on the current or voltage applied to a control electrode, or on the intensity of irradiation by infrared (IR), visible light, ultraviolet (UV), or X rays.

  • 30.2 Percent Efficiency – New Record for Silicon-based Multi-junction Solar Cell

    Wafer-bonded III-V / Si multi-junction solar cell with 30.2 percent efficiency. ©Fraunhofer ISE/A. Wekkeli

    Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with the Austrian company EV Group (EVG) have successfully manufactured a silicon-based multi-junction solar cell with two contacts and an efficiency exceeding the theoretical limit of silicon solar cells. For this achievement, the researchers used a “direct wafer bonding” process to transfer a few micrometers of III-V semiconductor material to silicon, a well-known process in the microelectronics industry. After plasma activation, the subcell surfaces are bonded together in vacuum by applying pressure. The atoms on the surface of the III-V subcell form bonds with the silicon atoms, creating a monolithic device.

  • Carbon Nanotubes Couple Light and Matter

    The formation of exciton-polaritons through strong light-matter coupling is a promising strategy for producing electrically pumped carbon-based lasers. Scientists from Heidelberg University and the University of St Andrews (Scotland) have now, for the first time, demonstrated this strong light-matter coupling in semiconducting carbon nanotubes. Figure: Arko Graf (Heidelberg University)

    Scientists from Heidelberg and St Andrews work on the basics of new light sources from organic semiconductors. With their research on nanomaterials for optoelectronics, scientists from Heidelberg University and the University of St Andrews (Scotland) have succeeded for the first time to demonstrate a strong interaction of light and matter in semiconducting carbon nanotubes. Such strong light-matter coupling is an important step towards realising new light sources, such as electrically pumped lasers based on organic semiconductors. They would be, amongst other things, important for applications in telecommunications. These results are the outcome of a cooperation between Prof. Dr Jana Zaumseil (Heidelberg) and Prof. Dr Malte Gather (St Andrews), and have been published in “Nature Communications”.

  • Humboldt Fellowship for research on tunable optical surfaces for Terahertz technology

    Dr. Corey Shemelya. Thomas Koziel/TU Kaiserslautern

    U.S. scientist Dr. Corey Shemelya has recently started a research stay at the University of Kaiserslautern in the form of a fellowship granted by the Alexander von Humboldt Foundation. Dr. Shemelya is studying structured optical surfaces which hold potential applications in communication technology and Terahertz imaging, e.g. body scanning equipment for airport safety. Shemelya is working in conjunction with the Terahertz Technology Laboratory of Professor Marco Rahm at the Department of Electrical and Computer Engineering and the State Research Center for Optical and Material Sciences (OPTIMAS).

  • IHP presents the fastest silicon-based transistor in the world

    The cross section shows a SiGe HBT of the latest generation, recorded by a TEM. The measurement curves are used to determine the transit frequency and the maximum oscillation frequency. © IHP 2016

    Frankfurt (Oder)/San Francisco. Scientist Dr. Bernd Heinemann of IHP – Innovations for High Performance Microelectronics will present results on silicon-germanium heterobipolar transistors (SiGe HBTs) developed in Frankfurt (Oder) on the “International Electron Devices Meeting” (IEDM) in San Francisco. His contribution titled “SiGe HBT with fT/fmax of 505 GHz/720 GHz “ presents speed parameters that set new standards for silicon transistors. “To present at IEDM is a valuable conclusion of the project ‘DOTSEVEN’, funded by the European Union. Together with Infineon and twelve other project partners from a total of six countries, the four-year project focused on developing SiGe HBTs with a maximum oscillation frequency, which is also referred to as fmax, of 0.7 THz,” says Dr. Bernd Heinemann, project manager at IHP.

  • Improvement of the operating range and increasing of the reliability of integrated circuits

    The invention is especially advantageous for oscillator circuits that are installed in radar devices for automotive assistance systems, for example. Foto: TLB GmbH

    Fast integrated circuits (ICs) are used in many ways in applied electronics. Especially, for hard driven fast or high-power components in the circuit, however, there is often a risk of breakdown, e.g. in oscillator circuits (radar systems, etc.) or “smart power” circuits. At the pn junctions present in all components, the breakdown occurs starting at a critical field strength. The circuit is thus destroyed or becomes unusable. A photodiode-controlled feedback prevents breakdown at pn junctions.
    TLB GmbH supports the University of Stuttgart in patenting and marketing its innovation.

  • Making spintronic neurons sing in unison

    Johan Åkerman. Photo: Johan Wingborg

    What do fire flies, Huygens’s wall clocks, and even the heart of choir singers, have in common? They can all synchronize their respective individual signals into one single unison tone or rhythm. Now researchers at University of Gothenburg have taught two different emerging classes of nano-scopic microwave signal oscillators, which can be used as future spintronic neurons, to sing in unison with their neighbours. Earlier this year, they announced the first successful synchronization of five so-called nano-contact spin torque oscillators. In that system, one of the nano-contacts played the role of the conductor, deciding which note to sing, and the other nano-contacts happily followed her lead.

  • Neues Licht dank Nanostrukturen

    Neues Licht dank Nanostrukturen © Universität Duisburg Essen

    Künftig sollen sie das Innere der Handtasche erhellen oder abendliche Jogger aus dem Dunklen hervorheben: Lichtemittierende elektrochemische Zellen, LECs, bieten gegenüber den bekannten LEDs viele Vorteile, aber noch hapert es – ja, am rechten Licht. Bisher sind nur gelb leuchtende LECs geeignet für den realistischen Einsatz. Für neutraleres Licht braucht man aber mindestens eine weitere Lichtfarbe. Forscher vom Center for Nanointegration (CENIDE) der Universität Duisburg-Essen (UDE) konnten nun erstmals die Farbe gezielt verändern und gleichzeitig die Leistungsfähigkeit der LECs steigern.

  • Novel light sources made of 2D materials

    Artistic representation of a two-photon source: The monolayer (below) emits exactly two photons of different frequencies under suitable conditions. They are depicted in red and green. (Picture: Karol Winkler)

    Physicists from the University of Würzburg have designed a light source that emits photon pairs. Two-photon sources are particularly well suited for tap-proof data encryption. The experiment's key ingredients: a semiconductor crystal and some sticky tape. So-called monolayers are at the heart of the research activities. These "super materials" (as the prestigious science magazine "Nature" puts it) have been surrounded by a virtual hype in the past ten years. This is because they show great promise to revolutionise many areas of physics.

  • Organische Chemie erweitert Funktionalität von Halbleitern

    Schnittstelle zwischen Halbleitertechnologie und organischer Chemie: Cyclooctin heftet sich selektiv an eine Siliziumoberfläche, so dass weitere funktionale Gruppen frei bleiben. (Abb.: Marcel Reutzel & Michael Dürr)

    Aus der Trickkiste der Organischen Chemie: Aktuelle Erkenntnisse mittelhessischer Chemiker und Physiker versprechen, die Halbleitertechnik um vielfältige Anwendungen zu erweitern. Die Forscher schafften es, organische Moleküle mit einer definierten Haftstelle auf Siliziumoberflächen zu verankern. Tragen die organischen Moleküle ausgewählte Anhänge, so bleiben diese frei, um ihre Funktion zu entfalten. Das Team des Sonderforschungsbereichs „Struktur und Dynamik innerer Grenzflächen“ (SFB 1083) berichtet in der aktuellen Ausgabe der Fachzeitschrift „Journal of Physical Chemistry“ über ihre Ergebnisse.

  • Scientists shrink electron gun to matchbox size

    A miniature electron gun driven by Terahertz radiation: An ultraviolett pulse (blue) back-illuminates the gun photocathode, producing a high density electron bunch inside the gun. The bunch is immediately accelerated by ultra-intense single cycle Terahertz pulses to energies approaching one kilo-electronvolt (keV). These high-field optically-driven electron guns can be utilized for ultrafast electron diffraction or injected into the accelerators for X-ray light sources. Credit: W. Ronny Huang, CFEL/DESY/MIT

    Terahertz technology has the potential to enable new applications.In a multi-national effort, an interdisciplinary team of researchers from DESY and the Massachusetts Institute of Technology (MIT) has built a new kind of electron gun that is just about the size of a matchbox. Electron guns are used in science to generate high-quality beams of electrons for the investigation of various materials, from biomolecules to superconductors. They are also the electron source for linear particle accelerators driving X-ray free-electron lasers.

  • Smaller, more efficient energy-saving chips “made in Europe”

    EPPL strengthened European industry and research by innovating advanced semiconductor products made in Europe CTR

    Research project led by Infineon successfully completed. Joint press information from the partners in the European research project “Enhanced Power Pilot Line”.

  • Speeding up digital performance using engineered light

    A semiconductor connected to metal electrodes is exposed to an ultra-short laser pulse, generating and steering directly measurable electric currents. Graphic: Christian Hackenberger

    In an experiment carried out at MPQ, the fastest ever switching of electric currents in semiconductors has been achieved with few-cycle laser pulses. Modern electronics and digital technologies rely on the control of electric current in semiconductor devices, from computers to smartphones and amplifiers. An international study by scientists from Monash University (Melbourne, Australia) and the Max Planck Institute of Quantum Optics (Garching, Germany) lays foundations for a dramatic performance increase of semiconductor-based signal-processing technologies.

  • The energy-saving data glasses

    Fraunhofer researchers have developed an energy-saving display that reduces the power consumption to a fraction. © Fraunhofer FEP, Photographer: Anna Schroll

    Data glasses mirror information to the eye without interfering with the wearer‘s vision. However, the battery runs down quickly, because the electronics consume a great amount of electricity while playing back the images. Fraunhofer researchers have developed an energy-saving display that reduces the power consumption to a fraction. The new display will be presented at the electronica trade fair in Munich from November 08-11, 2016.

  • Transporting more electricity through new lines

    Both the wires in the core and the aluminium zirconium wires in the jacket contribute to the tensile strength.  © 3M Deutschland GmbH

    The volume of electricity generated by wind energy and photovoltaic systems is increasing in the German power grid. This electricity has to be transported over long distances to urban areas and industrial centres. Newly developed high-temperature conductors now offer a way of increasing the maximum power capacity that can be transmitted through existing power lines. The BINE Projektinfo brochure entitled "The hotline in the grid" (13/2016) presents the new transmission lines. With a comparable conductor cross-section, these can almost double the transport capability of existing transmission lines.

  • TU Berlin: Stromventil für Nanostrukturen

    Nanostrukturen in blumenartiger Form. Die Abbildung zeigt die nanokristalline Oberfläche eines Indiumphosphids, enstanden durch elektrochemisches Ätzen.

    Forscher finden Methode zur Kontrolle von Stromschwankungen in extrem kleinen Bauteilen. Schwankungen des elektrischen Stroms können massive Probleme beim sicheren Betrieb von Geräten wie Computern, TV-Geräten oder Werkzeugmaschinen verursachen. In vielen elektronischen Bauteilen können sie durch Regelkreisläufe ausgeglichen werden. Schwierig wird es allerdings bei sehr kleinen Bauteilen, zum Beispiel in Nanostrukturen, denn hier müssen quantenmechanische Fluktuationen von einzelnen Elektronen kontrolliert werden. Forscher an der TU Berlin und der Universität Hannover haben nun experimentell mit einer modernen Messmethode gezeigt, wie sich zufällige Stromschwankungen bei quantenmechanischen Tunneln in Einzel-Elektronen-Transistoren kompensieren lassen. Ihre Ergebnisse veröffentlichten sie in der „Nature Nanotechnology“.