ATOMIC REARRANGEMENT AT THE INTERFACE OF ANNEALED ZNSE FILMS GROWN ONVICINAL SI(001) SUBSTRATES

Significant atomic rearrangement at the interface was found to take pl ace after post-growth annealing treatments of epitaxial ZnSe on As-pas sivated Si(001) substrates which were tilted by 4 degrees towards the [1 $($) over bar$$ 10] direction. The thermal stability of the ZnSe/As :Si interface was studied by rapid thermal annealing at temperatures u p to 960 degrees C after growing an epitaxial GaAs cap layer to preven t evaporation of the ZnSe during the anneals. The ZnSe/As:Si interface was examined by high-resolution electron microscopy. After an anneal at 900 degrees C the ZnSe/As:Si interface transformed from an atomical ly smooth interface found in the as-grown films to a facetted structur e with {111}-oriented sidewalls that extended preferentially in the [1 $($) over bar$$ 10] direction. The 60 degrees dislocations that were previously observed along this direction combined into closely spaced pairs or into Lomer dislocations which were associated with the facets . We present a model for the atomic structure of the facetted interfac e which is consistent with the experimental data and satisfies electro n-counting considerations. Total-energy calculations of the ZnSe/As:Si (001) interface were compared with those for the {111} interfaces seen after facetting.