DIFFUSE-SCATTERING IN PARTIALLY ORDERED III-V SEMICONDUCTOR ALLOYS

Features of diffuse scatterings in III-V semiconductor alloys grown on a (001) substrate have been investigated by Monte Carlo simulation, o n the basis of a simple kinetic Ising model we proposed previously. At omic arrangements and their Fourier power spectra were compared with p revious experimental results reported by other researchers. An epilaye r includes numerous (001) plane faults and platelike CuPt(L1(1))-type ordered phases perpendicular to the growth direction. They give rise t o the streaks along the [001] direction in an electron diffraction pat tern. Our simulated result shows that the existence of like-atom clust ers among the ordered domains causes the diffuse streaks drawn toward the fundamental lattice spots of a zinc-blende structure. With the pro gress of ordering, the wavy streaks become straightlike in shape and t he position of their intensity maximum shifts from the -(1/2 - delta), 1/2 - delta,0 (delta>0) to the ($) over bar 1/2 1/2 1/2 in the recipr ocal lattice space. The results obtained here have explained quite wel l some characteristic features of the CuPt ordering in epilayers revea led by experiments. We also discussed the ordering process during the epitaxial growth by using Warren-Cowley parameters.