INGAAS EPILAYERS OF HIGH IN COMPOSITION GROWN ON GAAS SUBSTRATES BY MOLECULAR-BEAM EPITAXY

Thick (2 mu m) InzGa1-zAs epilayers of high In composition have been g rown on (100) GaAs substrates, and the quality and the growth mode of the epilayers have been investigated by reflection high-energy electro n diffraction, double-crystal X-ray diffraction and scanning (reflecti on) electron microscopy. In the range of pi>0.8, three-dimensional isl ands are formed at the initial stage of the growth, and during island growth, strain due to the lattice mismatch is almost completely releas ed through the generation of dislocations. When the average size of th e islands exceeds about 50 nm, coalescence occurs among the islands ea ch of which is almost free from strain. Therefore, after the occurrenc e of island coalescence, the epilayers can grow without suffering misf it strain, and highly dislocated layers are confined within a narrow r egion neighboring the interface.