Investigation of the dosage effect on the activation of arsenic- and boron-implanted low-pressure chemical vapor deposition (LPCVD) amorphous-silicon films

The dopant activation of arsenic- and boron-implanted low-pressure chemical vapor deposition (LPCVD) amorphous silicon (α-Si) films, furnace-annealed with different annealing temperatures has been investigated. For the arsenic-implanted specimens with a dosage of 4 × 1014 cm−2, an increase of sheet resistance was observed with increasing annealing temperature for the temperatures range from 700 to 850°C. The reverse annealing phenomenon is attributed to dopant segregation at grain boundaries and becomes less marked with heavier doped films (2 × 1015 cm−2). Consequently for a dosage of 1 × 1016 cm−2, the sheet resistance exhibits a monotonic decrease with increasing annealing temperature. As for the boron-implanted specimens, the reverse annealing phenomenon is not observed. It means that dopant segregation is not significant for boron-implanted films.