Effect of carbon on dopant-vacancy pair stability in germanium

Density functional theory calculations were used to study the interaction between carbon and isolated substitutional dopants (boron, gallium, aluminium, indium, silicon, tin, nitrogen, phosphorous, arsenic and antimony) and dopant-vacancy pairs in germanium. It is predicted that there is a range of different association preferences, with carbon being strongly bound in some cluster geometries and dopants and unbound in others. If dopant-carbon pairs form they can act as vacancy traps to form larger and bound clusters. As vacancies are important for diffusion and cluster formation in germanium, the results are discussed in view of recent experimental studies.