ELECTRIC SUBBANDS IN SI-DELTA-DOPED GAAS GROWN BY METALORGANIC CHEMICAL VAPOR-DEPOSITION

Shubnikov-de Haas and Van der Pauw Hall effect measurements at 1.5 K have been carried out to investigate the existence of a two-dimensional electron gas and to determine subband energies in Si-delta-doped GaAs grown by atmospheric pressure metalorganic chemical vapor deposition. The Shubnikov-de Haas measurements clearly show multiple oscillation periods, which vary dramatically with the angle between the magnetic field and the normal to the sample surface, indicative of the occupation of several subbands by quasi-two-dimensional electrons in a potential well. With the magnetic field in the plane of the interface, magnetoresistance oscillations are also clearly observed that are not periodic in the reciprocal of the magnetic field. Using these experimental results and a self-consistent numerical method which took into account the exchange-correlation effects, the electric subband energies were also determined.