Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 84: Poster: Electronic structure theory / Carbon (other than graphene) / Si, Ge, and SiC / III-V semiconductors (other than nitrides)

HL 84.19: Poster

Mittwoch, 2. April 2014, 17:00–20:00, P1

Temperature-dependent external quantum efficiency of Ga(AsBi) — •Philipp Vlacil, Nils Rosemann, Peter Ludewig, Kerstin Volz, and Sangam Chatterjee — Philipps-Universität Marburg, Marburg, Germany

Dilute bismuth-containing alloys of GaAs have recently gained a lot of interest due to the large band gap reduction of about 60meV per percentage of bismuth. This large bowing shifts the Band gap of the alloy towards the telecom wavelength for concentrations of about 10%. This band gap shift is a consequence of modifications to the valence bands rather than the conduction bands, which are shifted, e.g. when In or N are incorporated. Additionally, the spin orbit coupling is increased and the shift of the split-of valence band is significantly increased[1], inhibiting hole-related Auger recombination processes. Nevertheless, the rather large covalent radius of bismuth induces significant disorder effects in such alloys. To quantify these, we investigated two sets of Ga(AsBi)/GaAs bulk and multiple quantum well (MQW) samples with different Bi concentrations by temperature-dependent absolute photoluminescence spectroscopy using an integrating sphere mounted inside a closed-cycle cryostat. The temperature dependence of the luminescence is used to quantify disorder. [1] Appl. Phys. Lett. 91, 051909, (2007)