Regensburg 2007 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 9: Semiconductor Laser II

HL 9.7: Vortrag

Montag, 26. März 2007, 16:15–16:30, H13

Optical characterisation of Ga(AsSb) heterostructures — •Christina Bückers, Gunnar Blume, Angela Thränhardt, Christoph Schlichenmaier, Peter J. Klar, Gerhard Weiser, and Stephan W. Koch — Fachbereich Physik und Wissenschaftliches Zentrum für Materialwissenschaften, Philipps-Universiät Marburg

Ga(AsSb)/GaAs is one of the most promising material systems for room temperature VCSEL (vertical cavity surface emitting laser) operation at 1.3µm or even longer wavelengths. To enable emission in the desired regime Sb fractions of about 30-40% are required. An unresolved question remains the band alignment of Ga(AsSb) embedded between GaAs: While holes are certainly localised in the Ga(AsSb) layer, the confinement of the electrons is controversially discussed. This has major implications for the lasing performance.

In order to characterise the band alignment, Ga(AsSb)/GaAs quantum well structures are investigated. The lineshape of electroabsorption (EA) spectra is analysed by microscopic theory which offers an accurate determination of the conduction band offset between different layers: The calculations demonstrate that the offset is the most sensitive parameter for the lineshape of the EA spectra. Comparison of theoretical and measured spectra indicates a type II band alignment between Ga(AsSb) and GaAs with a conduction band offset of 40±20meV. Furthermore, information about the internal electric field in the quantum well region can be extracted.