DOTZER, R and FRIEDLAND, KJ and HEY, R and KOSTIAL, H and MIEHLING, H and SCHOEPE, W (1994) LOW-TEMPERATURE ELECTRONIC TRANSPORT MEASUREMENTS ON A GATED DELTA-DOPED GAAS SAMPLE - MAGNETORESISTANCE, QUANTUM HALL-EFFECT AND CONDUCTIVITY FLUCTUATIONS. SEMICONDUCTOR SCIENCE AND TECHNOLOGY, 9 (7). pp. 1332-1339. ISSN 0268-1242,
Full text not available from this repository.Abstract
We present magnetotransport measurements (up to 7 T) performed at very low temperatures (down to 20 mK) on a GaAs sample containing two parallel delta-doped layers whose carrier concentration can be varied by means of a gate electrode. With increasing negative gate voltage the resistance becomes,more strongly temperature-dependent, indicating a more localized electron system. The magnetoresistance is found to be strongly anisotropic. When the field is parallel to the layers we find a large positive magnetoresistance which we attribute to orbital shrinking of the strongly localized donor wavefunction. In contrast, in the perpendicular orientation, we observe a strong negative magnetoresistance at low fields whose origin remains unclear, and the quantum Hall effect at larger fields. At low gate voltages both delta-layers are in the quantum Hall state whereas at larger negative voltages the layer adjacent to the gate becomes insulating. In the case of strong depletion the high-ohmic sample shows reproducible conductivity fluctuations as a function of either the gate voltage or the magnetic field. The fluctuations diminish at higher temperatures and larger measuring currents.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | RANGE-HOPPING REGIME; NEGATIVE MAGNETORESISTANCE; CONDUCTANCE FLUCTUATIONS; MECHANISM; FIELD; |
| Depositing User: | Dr. Gernot Deinzer |
| Last Modified: | 19 Oct 2022 08:40 |
| URI: | https://pred.uni-regensburg.de/id/eprint/53222 |
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