ELECTRON-MICROSCOPY AND X-RAY-DIFFRACTION CHARACTERIZATION OF INP GAAS GROWN BY ATOMIC LAYER EPITAXY

Atomic layer epitaxy has been found to be effective in achieving 2-dim ensional growth of highly mismatched InP/GaAs heterostructures from th e initial stages. The structural characterization of the layers has be en carried out by conventional and high resolution transmission electr on microscopy and high resolution x-ray diffractometry. 60-degrees typ e misfit dislocations have been observed at the heterointerface in all the structures investigated. As the layer thickness increases, neighb oring 60-degrees dislocations can react to form 90-degrees edge type d islocations. Planar defects extending into the layers along the {111} planes have also been observed. Finally, the elastic strain relaxation has been correlated with the nature and density of the observed cryst al defects.