CRYSTALLOGRAPHIC TILTING IN HIGH-MISFIT (100) SEMICONDUCTOR HETEROEPITAXIAL SYSTEMS

A model is presented for the formation of crystallographic tilting (mi sorientation) in highly mismatched (100) oriented zinc-blende semicond uctor heteroepitaxial layers grown on vicinal substrates. The model is based on the asymmetric generation of 60 degrees misfit dislocations upon island coalescence in the initial growth process-and the asymmetr ic strain release at substrate steps, and predicts a correlation betwe en tilt angle and initial growth planarity. Good agreement is found be tween model and experimental data on the GaAs/Si and other systems. It is also shown that, if the net tilt is small, an azimuthal rotation o f the tilt axis may occur, even if the system symmetry would hinder it . The influence of thermal annealing and thermal mismatch on the tilt is discussed as well. (C) 1996 American Vacuum Society.