GROWTH MODES AND RELAXATION MECHANISMS OF STRAINED INGAAS LAYERS GROWN ON INP(001)

Reflection high-energy electron diffraction and transmission electron microscopy were used to study the growth mode and relaxation of InxGa1-xAs layers, grown by molecular-beam epitaxy, mismatched relative to their In0.53Ga0.47As/InP(001) substrates, as a function of In composition and growth temperature (450 and 525-degrees-C). Weakly mismatched (almost-equal-to 1%) layers grow layer-by-layer and relax through a regular cross-grid type 60-degrees misfit dislocation network. Strongly mismatched (almost-equal-to 3%) layers begin to grow layer-by-layer, then grow with coherent three dimensional (3D) islands and relax through a tangled array of short edge dislocations. For an intermediate mismatch (almost-equal-to 2%), a 3D growth mode is observed at high-temperature (525-degrees-C) which leads to a tangled dislocation array; lowering the growth temperature to 450-degrees-C forces a two-dimensional growth mode producing a regular network of 60-degrees and edge dislocations.