Arsenic segregation in polycrystalline silicon

Dopant segregation at grain boundaries in polycrystalline silicon has been investigated. Arsenic was ion implanted into low-pressure, chemically vapor-deposited polycrystalline-silicon films. All films were then annealed at 1000 °C for 1 h, and some were subsequently further annealed at 800, 850, or 900 °C for 64, 24, or 12 h, respectively. The room-temperature resistivity of the films and the carrier Hall mobility were found to be higher after annealing at lower temperatures. By successively annealing the same sample at lower and higher temperatures, the resistivity would repeatedly increase and decrease, indicating dopant segregation. The heat of segregation was calculated to be 10.2 kcal/mol.