Observation of the transition associated with real-space transfer of a two-dimensional electron gas to a three-dimensional electron distribution in semiconductor heterolayers

The transport of electrons in semiconductor heterolayers under the influence of high crossed electric and magnetic fields has been investigated. Particular attention has been paid to real-space transfer effects. For the first time it is shown in a direct fashion that real-space transfer is associated with a transition of the two-dimensional electron gas to a three-dimensional electron distribution. This transition manifests itself by the sudden appearance of magnetoresistance (positive or negative) in perpendicular electric and magnetic fields at a critical electric field strength. Experimental results for various strengths and orientations of the magnetic field are presented and compared with a Monte Carlo transport simulation which included the Lorentz force.