Nano-scale dislocation patterning in PbTe on PbSe (1 0 0) heteroepitaxy studied by UHV scanning tunneling microscopy

Strain relaxation in the heteroepitaxial system PbTe on PbSe (100) is studied using scanning tunnelling microscopy. It is shown that a 2D surface morphology is sustained for all PbTe layer thicknesses, and that strain relaxation takes place by pure edge-type misfit dislocations. The dislocations are found to form an extremely regular square network. Its uniformity is based on the existence of a high dislocation mobility within the interface and an effective repulsive interaction between neighbouring dislocations. Because of its high regularity this nano-scale dislocation pattern could serve as template for the direct synthesis of self-assembled nanostructures.