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HL: Halbleiterphysik

HL 4: New materials

HL 4.4: Talk

Monday, March 27, 2006, 11:00–11:15, BEY 154

Band Offset Measurements of Quinternary (AlGaIn)(AsSb) — •Alexander Bachmann, Oliver Dier, Christian Lauer, Ralf Meyer, and Markus-Christian Amann — Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching

Current MIR antimonide-based type-I diode lasers reach a wavelength of up to 3.3 µm. These heterojunction devices use GaInAsSb with maximum 55% of In as quantum-well material and AlGaAsSb with 20% to 30% of Al as barrier material. To enlarge the wavelength further, the active material has to be adjusted. InAsSb has the smallest band gap in the (AlGaIn)(AsSb) system (0.283 eV according to 4.38 µm), but it has type-II alignment if used with AlGaAsSb as barrier material. Therefore, AlInAsSb or the quinternary AlGaInAsSb may be used yielding a type-I arrangement. As it is not possible to grow AlInAsSb with higher Al or In concentrations due to the formation of clusters and a large miscibility gap, Ga-dominated AlGaInAsSb has been used. Because of one more degree of freedom, it is possible to adjust the valence band offset (VBO) and the conduction band offset (CBO) almost independently within a certain range. For a diode laser a sufficiently large VBO for better hole-confinement and moderately large CBO for a homogeneous injection of the electrons in every quantum well are needed. However, band offset calculations from literature yield very different results, depending on the set of material parameters used. In this talk, we therefore present measured band-offsets (by C-V profiling) on MBE-grown quinternary samples of various material combinations to determine the optimal band alignments for type-I lasers.