Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 35: Semiconductor Laser

HL 35.9: Talk

Wednesday, March 25, 2009, 16:15–16:30, BEY 154

Single mode emitting GaInAsSb/GaSb quantum well lasers operating in continuous wave mode at 3.02 µm — •Thomas Lehnhardt, Michael Hümmer, Karl Rößner, Mirjam Müller, Sven Höfling, and Alfred Forchel — Technische Physik, Universität Würzburg, Germany

Mid-infrared lasers have attracted significant attention for highly sensitive tunable diode laser spectroscopy of gases. We report here on room temperature continuous wave single mode GaSb based quantum well (QW) lasers emitting at record long wavelength of 3 µm.

To obtain this long wavelength several challenges stemming from the GaInAsSb/GaSb material system have to be addressed. High In-contents are needed to realize narrow band gaps for long wavelength operation. In addition, quantization effects have to be reduced to avoid severe blue shifts. Therefore, thick QWs (17 nm) have to be grown, which necessitates higher As-contents in the GaInAsSb QWs. Too high As-contents however cause type-II band alignments. Thus, a compromise has to be found to keep a sufficient confinement for holes to avoid thermal emission from the QWs. With a commonly used band structure model, we estimate for our structures a valence band offset (VBO) in the range of only 20 meV. Nevertheless, we demonstrate with this approach state-of-the art single mode emitting distributed feedback lasers emitting 3 mW output power at room temperature, being ample for gas sensing applications.