The sign of the Hall effect in hydrogenated amorphous and disordered crystalline silicon

Hall experiments on a series of microcrystalline, microcrystalline-amorphous, amorphous and crystalline silicon samples with various defect densities are presented and discussed. Normal signs of the Hall effect in boron- and phosphorus-doped hydrogenated amorphous silicon have been observed. We interpret these results as due to a small volume fraction of nanocrystalline silicon, which falls below the detection limit of Raman experiments. Hydrogenated amorphous silicon, prepared under conditions far from microcrystalline growth, shows the known double-sign anomaly. On the other hand, sign reversals in crystalline silicon in which disorder was increased by silicon implantation up to apparently complete amorphization, were not found.