Regensburg 2022 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 25: Poster 1

HL 25.37: Poster

Mittwoch, 7. September 2022, 18:00–20:00, P2

Automation of band structure simulations to determine Si-dopant efficiency in AlGaAs — •Maximilian Kristo, Nico Brosda, Andreas D. Wieck, and Arne Ludwig — Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44801 Bochum, Germany

The potential landscape for electrons in semiconductor heterostructures is represented by its band structure.Their simulations can significantly help in the design of devices with new functionality. In order to systematically evaluate the doping efficiency in heterostructure samples, we automatized band structure calculations in a feedback loop with experimentally determined Hall parameters. These were determined by Van der Pauw measurements at 4.2 K.

The effective dopant concentration in the simulations was adapted to fit the experimental results and thus allowed to determine the effective dopant efficiency of Si doped AlGaAs HEMT structures to be compared with the dopant efficiency in Si doped GaAs samples. A majority of the dopant atoms are present in AlGaAs (with an aluminium concentration above 20 %) as deep impurities (Donor CompleX (DX) centers), which do not contribute to the electrical conductivity at 4.2 K if cooled in dark without bias. Therefore, these DX centers in Si doped AlGaAs lower the doping efficiency compared to Si doped GaAs. For AlGaAs with an aluminium concentration of 34 %, an average dopant efficiency of 14 ± 3 % and a negative correlation of -0.83 with the thickness of the doped layer could be found this way.