TEM STUDY OF THE EFFECT OF GROWTH INTERRUPTION IN MBE OF INGAP GAAS SUPERLATTICES

The influence of growth interruption during the MBE growth of (100) In0.5Ga0.5P/GaAs superlattices is investigated by cross-sectional TEM. A roughening of the growth front is observed during an interruption after the exchange of the group-V molecular beams. The roughening of growth front occurs due to a spontaneous change in the growth orientation of the superlattice from [100] to [311] directions. This change in growth orientation is characterized by an initial formation of V-shaped grooves with {311} facets on the GaAs growth front which eventually lead to the formation of regions of {311} superlattice structures. The direction of V-shaped grooves is along the [011BAR] axis, which is parallel to the surface dangling bonds of the group V atoms in the unreconstructed (100) plane. The most critical stage for the spontaneous change of the growth orientation is the interruption after the growth of a GaAs layer with the P2 flux.