Surfactants and antisurfactants are species, deposited prior to growth on the substrate to overcome fundamental limitations set by thermodynamics and adatom kinetics in a particular heteroepitaxial system. The role and mechanisms of surfactants and self-surfactants in the growth of group III-Nitrides is well established and understood. However, the physics governing the technological important example of Si as antisurfactant in GaN was under intensive debate.
In contrast to surfactants that mainly modify the growth mode by influencing adatom kinetics, we have revealed that antisurfactants modify the chemical potentials at the surface. This is based on the formation of a single monolayer of SiGaN3 subsurface layer that is electrically active and introduces a dipole moment caused by a charge transfer from the aforementioned layer to the surface. Hence, growth proceeds in a lateral epitaxial overgrowth way only at locations where the SiGaN3 layer is not present and allows to block and reduce the density of threading dislocations.