Ultrafast carrier dynamics in a GaN/Al0.18Ga0.82N superlattice

F. Mahler1, J.W. Tomm1, K. Reimann1, M. Woerner1, T. Elsaesser1, C. Flytzanis2, V. Hoffmann3, and M. Weyers3

Published in:

Phys. Rev. B, vol. 97, no. 16, pp. 161303(R) (2018).

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Abstract:

Relaxation processes of photoexcited carriers in a GaN/Al0.18Ga0.82N superlattice are studied in femtosecond spectrally resolved reflectivity measurements at ambient temperature. The transient reflectivity reveals electron trapping into defect states close to the conduction-band minimum with a 150-200 fs time constant, followed by few-picosecond carrier cooling. A second slower trapping process into a different manifold of defect states is observed on a time scale of approximately 10 ps. Our results establish the prominent role of structural defects and disorder for ultrafast carrier dynamics in nitride semiconductor structures.

1 Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany
2 Laboratoire Pierre Aigrain, École Normale Supérieure, 75231 Paris, France
3 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, 12489 Berlin, Germany