Defects and interfaces in low-temperature grown Ge/Si heterostructures

Abstract

Initial stages of misfit relaxation process in Ge epitaxial films grown by pulsed laser deposition on (001) Si substrates have been investigated by high-resolution transmission electron microscopy. Special emphasis is placed on conditions leading to a 2D (layer-by-layer) growth mode. The evolution of the dislocation network as a function of film thickness and thermal annealing is controlled by surface undulations and interactions between dislocations. The dislocation interactions leading to rearrangements in a nonequilibrium dislocation network driven by elastic interaction between parallel 60 degree(s) dislocation segments are discussed in detail. Based upon our experimental observations, we propose a model for the formation of stacking faults in heterostructures.