Influence of ion-irradiation parameters on defect formation in silicon films

It is shown that unlike bulk silicon, for which amorphization is observed at an irradiation dose of 5 × 10¹⁶ ion/cm², thin silicon films on sapphire are amorphized at lower critical doses (10¹⁵ ion/cm²). An undamaged surface layer remains when the silicon films are irradiated with Si⁺ ion beams. Its thickness depends on the current density of the incident beam. Rutherford backscattering studies show that annealing at 950°C improves the crystallinity of the irradiated silicon film. Annealing of the films at 1100°C leads to mixing of the silicon-sapphire interface.