Determination of transport parameters in amorphous Ni-P by infrared reflectivity and hall measurements

Abstract

We have measured the reflectivity in the spectral range 0.02–2.5 eV and the Hall resistivity up to 150 kilogauss of samples of electrodeposited amorphous Ni-P at room temperature. Analysis of the infrared data show that the density of states and inverse scattering time (1/τ) both decrease as P content is increased from 15 to 26 at. %. This result is consistent with rigid band models predicting d-band filling in this P concentration range. Hall measurements are complicated by magnetic enhancements which cause the Hall coefficient to change signs at about 23 at. % P. Measurements in the lowest concentration sample where separation of classical and anomalous Hall effect is possible indicate that the carriers are electron-like (negative classical Hall coefficient). The best quantitative estimates still imply a factor of 5 discrepancy between the IR and Hall determination of carrier density of states.