Magneto-transport in porous silicon

Magnetoresistance (MR) measurements have been performed in the temperature range 100-300 K on macroporous porous silicon (P.S.) samples. P.S. layers have been prepared by the anodic dissolution of Si in HF acid. The MR has been found to be positive in P.S. for the temperature range 100-300 K and for the entire range of magnetic field (0-5 kG). However the magnitude of the positive MR is found to be much less than expected on the basis of free electron conduction. Also the value of n in the relation Delta rho/rho(o) proportional to B(n) for the temperature range 100-300 K is found to be < 2, implying that there is a contribution of some phenomenon other than the flee electron conduction to MR. The measured data suggest that it is the contribution of localized state conduction near the Fermi level and in the localized states near the band edges. (C) 1997 Elsevier Science S.A.