Surface modifications due to strain relaxation in

Authors: Gunther Springholz

Publish Date: 1996

Volume: , Issue: , Pages: 277-302

PDF Link

Abstract

The different growth modes and strain relaxation processes in strained layer heteroepitaxy are studied for the case of molecular beam epitaxy of 21 latticemismatched EuTe on PbTe 111 Due to straininduced coherent islanding at high growth temperatures the growth proceeds in a StranskiKrastanow growth mode leading to the formation of regularly spaced three dimensional islands which can relaxe a significant part of the misfit strain by elastic deformation Due to the existence of a critical surface corrugation length strain induced 3D islanding can be kinetically suppressed and thus at low growth temperatures a 2D layerbylayer epitaxial growth mode can be sustained In such a case strain relaxation can occur only by the formation of misfit dislocations at the layersubstrate interface Using ultrahigh vacuum scanning tunneling microscopy it is shown that the injection of misfit dislocations at the critical layer thickness causes the appearance of monolayer surface step lines along the dislocation glide line directions During the course of strain relaxation the pileup of misfit dislocations leads to the formation of multiple step surface elevation leading to a considerable roughening of the epitaxial surface The course of this surface roughening can be understood by taking into account the kinetics of misfit dislocation formation

Keywords: