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Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 36: II-VI- and III-V-semiconductors

HL 36.5: Vortrag

Donnerstag, 4. April 2019, 10:45–11:00, H31

Molecular Beam Epitaxy Growth and Temperature-Dependent Electrical Characterization of Carbon-Doped GaAs on GaAs(111)B — •Tobias Henksmeier, Alexander Trapp, Stepan Shvarkov, and Dirk Reuter — Department of Physics, University of Paderborn, Warburger Straße 100, Germany

Molecular beam epitaxy (MBE) of III-V semiconductors on (111)-oriented surfaces has gained much interest in recent years due to the high symmetry of this surface. Carbon serves as a suitable p-type dopant on such surfaces.
We present a study of carbon doping of GaAs layers on (111)B semi-insulating 3" GaAs substrates with a 1 miscut towards (211) employing a heated graphite filament carbon source. GaAs(111)B samples of different carbon concentrations up to N=3× 1020 cm−3 were fabricated. Atomic force microscopy revealed smooth surfaces up to the highest carbon concentration. The overall carbon concentration was determined by SIMS and Hall measurements in van-der-Pauw geometry revealed p-type conductivity for all samples. Carrier freeze out was observed for low carbon concentrations at low temperatures while an almost temperature-independent conductivity and hole concentration is observed above N=1×1019 cm−3 which indicates degeneracy. Almost 100 % of the carbon is incorporated as an acceptor up to N=1×1019 cm−3. For higher concentrations, compensation sets in. The carbon activation energy in the GaAs(111)B oriented sample is determined by photoluminescence measurements to 26.3 meV and is verified by a hole density Arrhenius plot.

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