Resistivity of boron-doped polycrystalline silicon

The doping dependence of the resistivity of polycrystalline silicon deposited by low-pressure chemical vapor deposition and implanted with boron is investigated. At doping concentrations <1018 cm−3, the resistivity is almost two orders of magnitude larger than that of crystalline silicon. At very large doping levels (=1020 cm−3), the resistivity is comparable to that of crystalline silicon though slightly higher. Boron segregation at grain boundaries is not observed for doping levels <1019 cm−3. At 1020 cm−3, boron segregation or additional clustering at grain boundaries causes a reversible change in the resistivity upon changing the annealing temperature.