Critical behavior of the Hall coefficient of Si:P at the metal-insulator transition

Measurements down to 0.06 K indicate that the Hall coefficient of Si:P diverges as the metal-insulator transition is approached, in contrast with an earlier report by Koon and Castner for Si:As, and in disagreement with their claim for Si:P. We show that zero-temperature extrapolations deduced from data above 0.5 K, the range used in the earlier experiments, can yield a Hall coefficient that appears to remain finite.