Structural and energy characteristics of native vacancy-type defects in the biaxially stressed GaN lattice

For biaxially stressed GaN clusters, the structure, charges, and energies of the formation of intrinsic Ga and N vacancies are calculated by the quantum-chemical method in the SCF MO LCAO approximation taking into account relaxation of the crystalline surroundings. It is established that the use of substrates introducing compressive or tensile stresses into the epitaxial layer affects the concentrations of intrinsic vacancy-type point defects. This effect most clearly manifests itself in the nitrogen sublattice in the GaN crystal lattice, especially in the case of its tension, i.e., during the epitaxial grown of GaN on the Si substrate. Redistribution of the electron density in the defect region in the case of lattice compression or tension can be the cause of variation in the location of electronic levels of defects in the band gap of the crystal.