ELECTRON-TUNNELING IN HETEROSTRUCTURES WITH A SINGLE BARRIER AND SYMMETRICAL SPACERS IN A LONGITUDINAL MAGNETIC-FIELD

In GaAs/AlAs/GaAs heterostructures with a single AlAs barrier 50, 35, and 25 Angstrom thick and weakly doped spacers approximate to 600 Angs trom thick along both sides of the barrier tunneling-current oscillati ons are experimentally detected, with a period inversely proportional to the longitudinal magnetic field B. In these structures, when an ext ernal bias voltage is applied to the emitter side of the barrier a two -dimensional (2D) enriched layer is formed. An analysis of the experim ental data showed that it is impossible to determine the 2D electron c oncentration from the oscillation period; only the total number of 2D states in the enriched layer, below the Fermi level of the emitter vol ume, can be determined. (C) 1995 American Institute of Physics.