ELECTROOPTICAL PROPERTIES OF THE SI DELTA-DOPED GAAS ALGAAS TRIPLE-BARRIER RESONANT-TUNNELING STRUCTURE/

The electrooptical properties of a Si delta-doped GaAs/Al0.3Ga0.7As tr iple-barrier resonant tunneling (TRT) nanostructure have been studied by photoreflectance spectroscopy from 20 K to room temperature. The TR T structure forms two coupled quantum wells. The first and the second electronic subbands in the wide well are partially filled, and the cor responding optical transitions are suppressed. The strongest spectral feature is due to the enhancement of the subband resonance between the two coupled wells. The ionized delta-doping centers in the Al0.3Ga0.7 As side barriers can induce internal electric fields, and cause oscill atory spectral features when the photon energy is larger than the gap of Al0.3Ga0.7As. Analyzing the oscillatory part of the spectrum gives an internal electric field of 32 kV/cm, and an estimation of the elect ron subband energy in the ionized delta-doping center induced potentia l wells.