230 research outputs found
Uit de diepten : Nederlandse egodocumenten over de nazi concentratiekampen
Halsema, J.D.F. van [Promotor]Harskamp, A. van [Copromotor
Magnetotransport in a pseudomorphic GaAs/GaInAs/GaAlAs heterostructure with a Si delta-doping layer
Magnetotransport properties of a pseudomorphic
GaAs/Ga0.8In0.2As/Ga0.75Al0.25As heterostructure are investigated in pulsed
magnetic fields up to 50 T and at temperatures of T=1.4 K and 4.2 K. The
structure studied consists of a Si delta-layer parallel to a Ga0.8In0.2As
quantum well (QW). The dark electron density of the structure is n_e=1.67x
10^16 m^-2. By illumination the density can be increased up to a factor of 4;
this way the second subband in the Ga0.8In0.2As QW can become populated as well
as the Si delta-layer. The presence of electrons in the delta-layer results in
drastic changes in the transport data, especially at magnetic fields beyond 30
T. The phenomena observed are interpreted as: 1) magnetic freeze-out of
carriers in the delta-layer when a low density of electrons is present in the
delta-layer, and 2) quantization of the electron motion in the two dimensional
electron gases in both the Ga0.8In0.2As QW and the Si delta-layer in the case
of high densities. These conclusions are corroborated by the numerical results
of our theoretical model. We obtain a satisfactory agreement between model and
experiment.Comment: 23 pages, RevTex, 11 Postscript figures (accepted for Phys. Rev. B
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