Strain relaxation and dislocation formation for PbTe molecular beam epitaxy on 5.2% lattice-mismatched (001)PbSe substrates was studied using in situ reflection high-energy electron diffraction and scanning tunneling microscopy. For layers exceeding 1 monolayer in thickness misfit dislocations were formed along the fourfold in-plane <110> directions within the layer/substrate interface. These misfit dislocations were of pure edge type with a ½[110] type Burgers vector parallel to the interface. At layers exceeding about 5ML, remarkably regular square arrays of misfit dislocations were formed with a dislocation spacing of 10nm and a high uniformity of the spacings of ±12%. This was due to the mutual lateral elastic repulsion between the dislocations as well as the fact that the (001) interface was a preferred dislocation glide plane in the lead salt compounds. Strain Relaxation and Dislocation Patterning in PbTe/PbSe (001) Lattice-Mismatched Heteroepitaxy. K.Wiesauer, G.Springholz: Applied Surface Science, 2002, 188[1-2], 49-54