SURFACE RIPPLES, CROSSHATCH PATTERN, AND DISLOCATION FORMATION - COOPERATING MECHANISMS IN LATTICE MISMATCH RELAXATION

We study the interplay of elastic and plastic strain relaxation of SiG e/Si(001). We show that the formation of crosshatch patterns is the re sult of a strain relaxation process that essentially consists of four subsequent stages: (i) elastic strain relaxation by surface ripple for mation; (ii) nucleation of dislocations at the rim of the substrate fo llowed by dislocation glide and deposition of a misfit dislocation at the interface; (iii) a locally enhanced growth rate at the strain rela xed surface above the misfit dislocations that results in ridge format ion. These ridges then form a crosshatch pattern that relax strain ela stically. (iv) Preferred nucleation and multiplication of dislocations in the troughs of the crosshatch pattern due to strain concentration. The preferred formation of dislocations again results in locally enha nced growth rates in the trough and thus leads to smoothing of the gro wth surface. (C) 1995 American Institute of Physics.