HIGH-RESOLUTION X-RAY-DIFFRACTION AND SCATTERING MEASUREMENT OF THE INTERFACIAL STRUCTURE OF ZNTE GASB EPILAYERS/

The surface and interface structures of ZnTe epilayers grown by molecu lar beam epitaxy on GaSb (001) substrates under different conditions h ave been investigated by high resolution x-ray diffraction and grazing incidence scattering. Reciprocal space mapping around the symmetrical diffraction reciprocal point 004 and asymmetrical diffraction point ( 115) over bar showed that the ZnTe epilayers, in the samples investiga ted, were fully strained to the substrate, The crystalline quality of the ZnTe epilayer grown on a substrate annealed in a Zn flux was very good, while evidence for an interfacial layer, of thickness varying fr om 2-20 nm, was found when the substrate was annealed in a Te flux pri or to growth. This is attributed to Ga2Te3 formation at the interface. The interfacial layer roughens the interface and surface, and both cr ystal truncation rod measurements and grazing incidence x-ray reflecti vity show the surface roughness to be about 4 nm. Such a rough surface and interface is also inferred from the broader distribution along th e transverse direction in reciprocal space maps, A shorter lateral cor relation length is found for the roughness of the sample containing th e interfacial layer. The disappearance of interference fringes is attr ibuted to nonuniformity of the interfacial layer. (C) 1997 American In stitute of Physics.