TEM INVESTIGATIONS OF LP-MOVPE GROWN GAAS/GE HETEROSTRUCTURES

TEM investigations have been carried out on GaAs/Ge single heterostructures grown by Low Pressure Metalorganic Vapour Phase Epitaxy at different growth rate deposition and with different thicknesses of the epitaxial layer. Misfit dislocation networks have been observed in specimens with the epitaxial layer thicker than 0.45-mu-m: they were confined within 50 nm of the interface and were mainly of 60-degrees type. The samples grown at lower deposition rate exhibit twins at the heterointerface on the {111} composition planes.