Resistivity of boron and phosphorus doped polycrystalline Si1−<i>x</i>Ge<i>x</i> films

Abstract

Sheet resistance, Hall mobility, and effective carrier concentration as a function of annealing parameters for boron or phosphorus ion implanted films of polycrystalline Si, Si0.75Ge0.25, and Si0.50Ge0.50 films are presented. The films were ion implanted with boron or phosphorus at dosages between 5×1014 and 4×1015 cm−2, and then thermally annealed between 550 and 650 °C from 0.25 to 120 min. Boron doped films showed decreasing minimum sheet resistance with increasing Ge fraction, while phosphorus doped films exhibited the reverse trend. Both boron and phosphorus doped films showed minima as a function of anneal time. This is attributed to the competing processes of damage annealing versus dopant segregation. Poly-Si0.50Ge0.50 films achieved minimum resistance faster than poly-Si films, and the lowest sheet resistances were measured in boron doped, poly-Si0.50Ge0.50 films.