Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 108: Poster: Ultra-fast phenomena / Optical properties / Semiconductor laser / Devices and device concepts

HL 108.23: Poster

Donnerstag, 3. April 2014, 17:00–20:00, P1

Sub-Monolayer-Control in Epitactic Growth of Quantum Cascade Lasers — •Michael Kwiatek1, Negar Hekmat1,2, Arne Ludwig1, Nathan Jukam2, and Andreas D. Wieck11Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Deutschland — 2AG Terahertz-Spektroskopie und Technologie, Ruhr-Universität Bochum, Deutschland

A quantum cascade laser (QCL) consists of multiple vertically stacked semiconductor modules including several well-dimensioned quantum wells. In QCLs intersubband transitions in the conduction band generate the laser light. Due to QCL's cascading structure, one electron generates multiple photons. The production of good QCLs sets high demands on the fabricating process, especially on the layer quality of the quantum wells and barriers, why QCL fabrication is often performed with Molecular Beam Epitaxy (MBE). A known problem in MBE is the shutter transient of the effusion cells (EC). When the EC-shutter is closed, the heat of the EC is reflected back in itself. If the shutter is opened, more power is needed to stabilize the temperature and hence the material flux of the EC. For QCLs very thin material layers of only a few monolayers with high precision are crucial. The time the EC needs to stabilize leads to a change in the growth rate for those thin layers. Our goal is the reduction of the shutter transient effect on the QCL's layer structure. Therefore we want to investigate the time dependent growth rate change of the EC and apply countermeasures like aligned PID control parameters and/or an adapted shutter design.

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