Spinodal decomposition in InGaAsP epitaxial layers.

InGaAsP epitaxial layers emitting in the 1.25-137 micron wavelength region have been evaluated using transmission electron microscopy, X-ray diffraction and photoluminescence. Electron diffraction patterns show elongation of the 400 spots in the 100> direction and diffuse intensity on the low angle as well as on the high angle side. The observation is consistent with the extra scattering observed close to the 400 Bragg peaks by X-ray diffraction. Furthermore, microstructures exhibit quasi periodic fine scale structure having a wavelength of ~150 angstrom, rectilinear boundaries and a weakly developed basket-weave pattern. These observations are compatible with the occurrence of spinodal decomposition in the layers.