Berlin 2024 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 56: Heterostructures, Interfaces and Surfaces II

HL 56.1: Vortrag

Freitag, 22. März 2024, 09:30–09:45, EW 561

Magneto-optical studies of charge transfer excitons in type-II semiconductor quantum wells — •Johannes Röder1, Marina Gerhard1, Cong Ngo2, Johannes T. Steiner2, Mikko Wilhelm1, Christian Fuchs1, Wolfgang Stolz1, Stefan W. Koch1, Torsten Meier2, Wolfram Heimbrodt1, and Martin Koch11Department of Physics and Material Sciences Center, Philipps-Universität Marburg, Germany — 2Department of Physics, Paderborn University, Germany

While charge transfer excitons (CTX) are a well-known phenomenon in so called type-II semiconductors, their study with absorption measurements is very challenging, due to the small overlap between the electron and hole wave functions.

This situation was changed by growing 50 asymmetric double quantum wells (ADQWs) via MOVPE, for which earlier studies have already shown a strong CTX absorption. One ADQW consisted of a layer of Ga(As,Sb) and one layer of (Ga,In)As. Among the different samples the Sb-content was varied and a reference sample without the Ga(As,Sb)-layer was grown as well.

The main focus of this presentation is the CTX absorption behavior in a magnetic field. Here we observed the 1s CTXs shift and the formation of higher order excitons in magnetic fields up to 7 T at 1.8 K.

Theoretical calculations via the semiconductor-Bloch equations with a k.p model agree very well with or experimental results, thus confirming our observation of spatially indirect magneto-excitons.

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