Direct observation of above-barrier quasibound states in $In_xGa_{1-x}$As/AlAs/GaAs quantum wells

Abstract

We report the direct observation of numerous above-barrier quasibound states of potential barriers, formed by a thick layer of GaAs sandwiched between ultrathin AlAs interface layers in InxGa1-xAs/GaAs strained quantum wells. Interband transitions between the conduction and the valence subband up to n = 26 an clearly observed in the room-temperature photoreflectance spectra. Fairly good agreement is obtained between the peak positions and the calculated interband transitions of the quasibound states found in the GaAs barriers.