<strong>Semiconductor</strong> <strong>Physics</strong> <strong>Sectional</strong> <strong>Programme</strong> <strong>Overview</strong> HL 49 Devices Thu 15:15–16:30 BEY 154 HL 49.1–49.5 HL 50 Poster II Thu 16:30–19:00 P3 HL 50.1–50.109 HL 51 Invited Talk Eroms Fri 10:15–11:00 HSZ 01 HL 51.1–51.1 HL 52 Quantum dots and wires: Optical properties IV Fri 11:00–14:00 POT 151 HL 52.1–52.12 HL 53 Hybrid systems Fri 11:00–11:15 BEY 154 HL 53.1–53.1 HL 54 Metal-insulator transitions Fri 11:15–11:30 BEY 154 HL 54.1–54.1 HL 55 Photonic crystals Fri 11:30–13:15 BEY 154 HL 55.1–55.7 HL 56 Quantum dots and wires: Preparation and characterization III Fri 11:00–13:15 POT 51 HL 56.1–56.9 HL 57 Theory of electronic structure Fri 11:00–12:45 BEY 118 HL 57.1–57.7 Annual General Meeting of the Section <strong>Semiconductor</strong> <strong>Physics</strong> Thu 19:00–20:00 HSZ 01 Tagesordnung: 1. Begrüßung und Bericht 2. Stichwortkatalog 3. Verschiedenes
<strong>Semiconductor</strong> <strong>Physics</strong> Monday Sessions – Invited, Keynote, Contributed Talks and Posters – HL 1 Invited Talk Kneissl Time: Monday 09:30–10:15 Room: HSZ 01 Invited Talk HL 1.1 Mon 09:30 HSZ 01 From ultraviolet light emitting diodes to microcavity disk lasers - New frontiers in InAlGaN optoelectronics — •Michael Kneissl — Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, D-10123 Berlin, Germany Over the past decade group III nitrides have evolved into one of the most important and versatile semiconductor materials. GaN-based blue, green and white light emitting diodes as well as violet laser diodes are already commonplace and have entered many areas of everyday life. Here we will discuss some of the new fields of research for InAlGaN materials and devices and review progress in the development of deep ultraviolet light emitting diodes and lasers, growth and optical properties of InN and indium rich alloys, the role of GaN-based quantum dots for novel light emitters, and work on spiral microcavity disk lasers. HL 2 Symposium THz-quantum cascade lasers Time: Monday 10:15–12:45 Room: HSZ 01 Keynote Talk HL 2.1 Mon 10:15 HSZ 01 Designing the emission of THz Quantum Cascade Lasers with surface plasmon photonic structures — •Alessandro Tredicucci — NEST CNR-INFM , Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy The development of quantum cascade lasers operating at terahertz frequencies is proceeding at a very rapid pace. For their successful practical implementation, specific requirements have now to be addressed, particularly concerning the properties of the emitted radiation. Single-mode THz lasers with distributed feedback resonators have been achieved and a new technique involving surface plasmon gratings has been demonstrated to improve performances. The latter also offers the possibility of constructing distributed Bragg gratings as a replacement for high-reflection coatings or to implement vertical emitting devices. Solutions allowing broad tuneability are examined, either relying on external cavity set-ups or more unconventional external electrical control. Keynote Talk HL 2.2 Mon 10:45 HSZ 01 THz generation and mixing using Quantum Cascade Lasers — •Carlos Sirtori — Matériaux et Phénomènes Quantiques, Université Denis Diderot - Paris 7, Paris, France THz quantum cascade (QC) lasers are electrically pumped semiconductor devices based on electronic intersubband transition in quantum wells. Recently, we have been investigating lasers with emission frequency at 3THz and 1.9THz (λ = 100µm and λ = 160µm). The latter is the longest wavelength ever achieved in QC lasers without the help of a magnetic field. At 3THz we were able to obtain 100mW of peak power and a maximum operating temperature of 100K. After a brief introduction on the state-of-the-art, I will present our results on novel THz waveguide structures, allowing ”buried”structures and ultra-low threshold currents. Finally, I will introduce a scheme in which a beam at telecom frequencies can be injected into a QC lasers for coherent THz modulation and up-conversion. Keynote Talk HL 2.3 Mon 11:15 HSZ 01 Progress in single frequency and long wavelength quantum cascade lasers — •Jerome Faist 1 , G. Scalari 1 , L. Sirigu 1 , L. Ajili 1 , C. Walther 1 , M. Giovannini 1 , A. Dunbar 2 , and R. Houdre 2 — 1 University of Neuchâtel, Switzerland — 2 EPFL Lausanne, Switzerland The realization of terahertz QC lasers has attracted much attention because of its potential applications in imaging and spectroscopy. Spatial and spectral control of the mode profile are therefore of paramount importance. Single mode distributed feedback, as well as devices with photonic crystal mirrors will be demonstrated. Electrically switchable, multi-color emission based on magnetic confinement with a record low frequency of 1.39 THz will also be discussed. Finally, results with InPbased terahertz quantum cascade will be described. Keynote Talk HL 2.4 Mon 11:45 HSZ 01 Growth and Processing of GaAs quantum cascade lasers — •Gottfried Strasser, Aaron Maxwell Andrews, Tomas Roch, Gernot Fasching, Alexander Benz, Sebastian Golka, Maximilian Austerer, Christian Pfluegl, Werner Schrenk, and Karl Unterrainer — TU Wien, Zentrum für Mikro- und Nanostrukturen, Floragasse 7, 1040 Wien We report on growth and processing of GaAs-based quantum cascade lasers above and below the reststrahlenband. Despite the advances in mid-infrared (MIR) QCLs, THz QCLs remain difficult to fabricate. The tolerances in alloy composition, layer thickness, and doping are lower for THz QCLs than their MIR counterparts. Processing of GaAs QC lasers at THz frequencies isin spite of the relaxed dimensions, still a demanding task. This is particularly true for micro cavities. Double plasmon waveguides, single plasmon and double metal waveguide scenarios will be discussed. We will report about various THz resonators [1] (circular and ring shaped micro cavities) as well as surface emitting concepts (2nd order dfbs), where smart dfb designs can be used for wavelength selection of e.g. surface SHG [2] versus facet fundamental light output. [1] G. Fasching, A. Benz, K. Unterrainer, R. Zobl, A.M. Andrews, T. Roch, W. Schrenk, G. Strasser; ”THz Microcavity Quantum Cascade Lasers”; Appl. Phys. Lett. 87, (21.11.2005) [2] C. Pflügl, M. Austerer, W. Schrenk, G. Strasser; ”Second-harmonic generation in GaAs-based quantum-cascade lasers grown on substrates”; Electron. Lett., in print (2005) Keynote Talk HL 2.5 Mon 12:15 HSZ 01 GaInAs/AlAsSb quantum cascade lasers: a new approach towards 3-to-5 µm semiconductor lasers — •Joachim Wagner, Quankui Yang, Christian Manz, Wolfgang Bronner, Christian Mann, and Klaus Köhler — Fraunhofer-Institut für Angewandte Festkörperphysik (IAF), Tullastrasse 72, 79108 Freiburg, Germany Quantum cascade (QC) lasers based on the GaInAs/AlInAs-on-InP materials combination yield high-performance devices in the 5-to-10 µm wavelength range. These lasers can be operated in cw mode up to roomtemperature and in pulsed mode up to 400-500K. Towards shorter wavelengths GaInAs/AlInAs QC laser performance rolls off due to insufficient carrier confinement caused by the limited available conduction- band offset, which is in the 500-700 meV range. A more than twofold increase in con-duction band offset can be achieved when using lattice matched AlAsSb rather than AlInAs as barrier material. For the GaInAs/AlAsSb materials combination the offset for the direct conduction band minimum amounts to 1.6 eV. Compared to alternative con-cepts for large conduction band offset QC structures, such as the GaN/AlN or InAs/AlSb materials combinations, the present approach has the significant advantage to make use of the mature fabrication technology available for InP-based lasers. In spite of the challenges in materials growth, GaInAs/AlAsSb and even quaternary barrier GaInAs/AlGaAsSb QC lasers emitting in the 4-4.5
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