2-DIMENSIONAL PERSISTENT PHOTOCONDUCTIVITY AND MAGNETIC FREEZE-OUT IN LIGHTLY DELTA-DOPED INP

We present magnetotransport experiments on a lightly "δ" Si doped LP-MOCVD grown sample. As the temperature is lowered, the electron population decreases and becomes unmeasurably small below 160 K. An activation energy is deduced from the temperature dependence which is related to a "parasitic" deep center. At 4.2 K, optical excitation leads to a permanent increase of the carrier concentration. At saturation of the phenomenon, we observe a quantum Hall plateau on ρxy which corresponds to i = 2. For lower optical excitations, a lower carrier density is obtained. At high magnetic field (B > 10 T), we observe magnetic freeze-out (MFO) of the electron gas. The temperature dependence of the MFO gives an insight into the level trapping of the electrons and its magnetic field dependence. © 1990.