Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 31: Poster II

HL 31.56: Poster

Dienstag, 26. Februar 2008, 16:30–19:00, Poster D

Carbon doped high mobility 2D hole gas in GaAs/AlGaAs heterostructures — Christian Gerl, •Marika Kubová, Dieter Schuh, and Werner Wegscheider — Institut für Experimentelle und Angewandte Physik, Universität Regensburg, D 93040 Regensburg

Carbon as an acceptor in GaAs/AlGaAs heterostructures provides significant advantages in comparison with Si and Be acceptor materials. C-doped structures exhibit high mobility of two-dimensional hole gases (2DHGs) beyond 10^6 cm^2/Vs. It is possible to prepare structures in standard growth directions (in the (001) and (110) crystal plane) in contrast to Si-doped GaAs (311)A. Utilizing a carbon filament doping source, ultra high mobility quantum wells and modulation doped single interface structures in the GaAs/AlGaAs material system were prepared by molecular beam epitaxy (MBE). Hole mobility strongly depends on quantum well width and spacer thickness. Both parameters were optimised. Magnetotransport measurements at low temperatures show hole mobilities of 1.2*10^6 cm^2/Vs on GaAs (001) substrates. The carrier density reveals a hysteretic behaviour when tuned with an external electric field.