Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 96: Poster III C (III-V Semiconductors incl. Nitrides)

HL 96.11: Poster

Donnerstag, 19. März 2015, 14:00–20:00, Poster B

Type-II Excitons in (Ga,In)As/Ga(N,As)-quantum wells on GaAs — •Carsten Kruska, Sebastian Gies, Philip Hens, Wolfgang Stolz, Kerstin Volz, and Wolfram Heimbrodt — Faculty of Physics and Material Science Center, Philipps University Marburg, D-35032 Marburg, Germany

Quantum Well (QW) structures are used in many semiconductor devices. These systems inevitably contain interfaces, that influence the charge carriers. Since the recombination of type-II excitons takes place across the interface their properties are influenced by the interface, making type-II excitons an excellent probe to study internal interfaces. Here, we present an analysis of the recombination of spacially indirect (type-II) excitons in (Ga,In)As/Ga(N,As)-MQWs on GaAs.

The MQW structures under investigation were grown epitaxially using metal-organic vapor-phase epitaxy and consist of a (Ga,In)As-QW and a Ga(N,As)-QW separated by a GaAs interlayer of varying thickness. By adjusting the N-content the type-I or type-II behavior is achieved. The type-II transition between the electron in the Ga(N,As)-QW and the heavy hole in the (Ga,In)As-QW was observed and investigated depending on the interlayer thickness. Conjuction of experiment and QW-calculation using the transfer matrix method reveal the hetero-offset between the conduction bands of Ga(N,As) and GaAs to be 600 meV. For the heavy hole band within the errorbars no offset was found. Furthermore, time resolved measurements were performed to reveal the recombination dynamics of the type-II transitions and their interplay with the interface.