CROSS-SECTIONAL TRANSMISSION ELECTRON-MICROSCOPY AND SCANNING-TUNNELING-MICROSCOPY APPLIED TO INVESTIGATION OF PHASE SEGREGATION IN III-V MULTILAYERS GROWN BY MOLECULAR-BEAM EPITAXY

We report the results of a comparative investigation of cross-sectiona l transmission electron microscopy (XTEM) and cross-sectional scanning tunnelling microscopy (XSTM) applied to the study of InxGa1-xAsyP1-y layers grown by molecular-beam epitaxy (MBE). Contrast fluctuations pe rpendicular to the growth direction are observed using both techniques and the spatial wavelength of the contrast variation is the same in b oth types of image. The origin of the contrast is discussed; the XTEM contrast is due to strain-induced distortion of the lattice planes nea r the surface, while the XSTM contrast arises from differences in the local electronic structure within the InxGa1-xAsyP1-y layers. Both of these effects have the same root cause, namely phase segregation withi n the alloy layer during MBE growth.