Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 85: Poster Session II

HL 85.54: Poster

Donnerstag, 17. März 2011, 18:00–21:00, P4

Influence of interface roughness on relaxation rates and optical gain in a quantum cascade laser — •Milan Žeželj¹, Vitomir Milanović², Jelena Radovanović², and Igor Stanković¹ — ¹Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia — ²Faculty of Electrical Engineering, University of Belgrade, Bul. kralja Aleksandara 73, 11020 Belgrade, Serbia

We present a model for calculating the optical gain in a midinfrared GaAs/AlGaAs quantum cascade laser in a magnetic field, based on solving the set of rate equations that describe the carrier density in each level, accounting for the optical-phonon and interface roughness scattering processes. The confinement caused by the magnetic field strongly modifies the lifetimes of electrons in the excited state and results in pronounced oscillations of the optical gain as a function of the field. Numerical results are presented for the structure designed to emit at 11.4µm, with the magnetic field varying in the range of 10-60T, mean height of roughness is 0.15nm and correlation length 6nm. The effects of band nonparabolicity are also included. The conclusion of presented work is that influence of interface roughness scattering is not negligible and it gives a very important contribution in calculating optical gain of quantum cascade laser.