EVIDENCE OF ELECTRONIC CONFINEMENT IN PSEUDOMORPHIC SI GAAS SUPERLATTICES/

We report the observation of coupling between intersubband plasmons an d longitudinal-optical phonons in Si/GaAs superlattices pseudomorphica lly grown on GaAs-(001). Measurement of both phononlike (I-) and plasm onlike (I+) coupled modes by Raman scattering unambiguously demonstrat ed electronic confinement within pseudomorphic Si layers and allowed u s to determine the 0-->1 intersubband transition energy. Comparison wi th the results of tight-binding calculations indicated a type-I band a lignment across the Si/GaAs heterojunctions, with a conduction-band of fset of 0.61 eV and a valence-band offset of 0.25 eV.