  Heteroepitaxy enables the engineering of novel properties, which do not exist
in a single material. Two principle growth modes are identified for material
combinations with large lattice mismatch, Volmer-Weber and Stranski-Krastanov.
Both lead to the formation of three-dimensional islands, hampering the growth
of flat defect-free thin films. This limits the number of viable material
combinations. Here, we report a distinct growth mode found in molecular beam
epitaxy of PbTe on InP initiated by pre-growth surface treatments. Early
nucleation forms islands analogous to the Volmer-Weber growth mode, but film
closure exhibits a flat surface with atomic terracing. Remarkably, despite
multiple distinct crystal orientations found in the initial islands, the final
film is single-crystalline. This is possible due to a reorientation process
occurring during island coalescence, facilitating high quality heteroepitaxy
despite the large lattice mismatch, difference in crystal structures and
diverging thermal expansion coefficients of PbTe and InP. This growth mode
offers a new strategy for the heteroepitaxy of dissimilar materials and expands
the realm of possible material combinations.
