Defect complexes in fluorine-implanted germanium

In the present article we employ positron annihilation lifetime spectroscopy and secondary ion mass spectrometry to study the thermal evolution of vacancy related defects in fluorine-implanted germanium. We find that fluorine enriches the germanium matrix with various vacancy-like clusters that show both concentration and annealing temperature-dependent behaviour. We demonstrate that low fluorine concentrations saturate the Ge matrix with large concentrations of divacancy-like complexes that are effectively removed after moderate annealing. High fluorine concentrations, however, appear to stabilize a large component of monovacancy-like complexes in the near-surface region of the Ge substrates. These monovacancy-like complexes also appear to be thermodynamically stable, even after high-temperature annealing. The nucleation and thermal evolution of these vacancy-like defects may have particular importance in the fabrication and control of future germanium electronic devices.