MAGNETOTRANSPORT IN INP-BASED DILUTE SINGLE DELTA-LAYERS

We have investigated the magnetotransport in InP sulphur-doped delta-l ayer structures. In contrast to GaAs-based systems, it was possible to measure single delta layers in the concentration range between 10(15) and 10(16) m-2 where a metal-insulator transition is expected. At low magnetic fields perpendicular to the sample we observed a giant negat ive magnetoresistance (approximately 30% at 4.2 K), followed by an exp onential increase in magnetoresistance at high fields. The behavior of the minimum shows certain features of the quantum Hall effect corresp onding to a filling factor of 2. The experimental data are interpreted with the help of a strong-weak-localization transition-phase diagram in a disordered two-dimensional electron gas constructed using a simpl e lucid model.