Why are arsenic clusters situated at dislocations in gallium arsenide

The interaction of arsenic with dislocations in gallium arsenide has been studied. By performing molecular dynamics simulations with a Tersoff-type interaction potential and simulating the microscopic diffusion–drift–aggregation process based on the kick-out mechanism, we obtained that arsenic clusters are preferably situated at dislocations from energetic and kinetic reasons. This formation of arsenic clusters explains why the radius of the cylinder with an increased free electron concentration around dislocations in n-type sulfur-doped gallium arsenide extends up to about 10 μm, as revealed by Raman scattering.