CHARACTERIZATION OF GAAS/SI/GAAS HETEROSTRUCTURES

GaAs/Si(n)/GaAs, n = 1 to 3 mono-layers (ML) were grown on GaAs (100) substrates using molecular beam epitaxy. Double crystal X-ray diffraction rocking curve and Rutherford backscattering/chanelling studies indicated that 1 ML of Si grows coherently and psuedomorphicatly on GaAs and 2 and 3 ML Si exhibit increasing defect nature and are probably relaxed. Raman scattering measurements of the cap GaAs layer showed an increase in intensity of forbidden transverse optical (TO) phonon peak with increasing underlying Si layer thickness. Cross-sectional transmission electron microscopy studies revealed that for 1 ML Si, the Si-GaAs interface and the Si layer are defect free. However, for increasing thickness of Si to n = 2 and 3 ML, defect density increased at the Si-GaAs cap layer interface.