  We investigate the charge transport in a semiconductor nanowire that is
subject to a perpendicular magnetic field and in partial contact with an
\textit{s}-wave superconductor. We find that Majorana fermions, existing at the
interface between superconducting and normal sections of the nanowire within
certain parameter region, can induce resonant Andreev reflection of electrons
at the interface, which yields a zero energy peak in the electrical conductance
of the nanowire. The width of the zero energy conductance peak for different
experimental parameters is characterized. While the zero energy peak provides a
signature for Majorana fermions in one dimensional nanowires, it disappears in
a two-dimensional semiconductor thin film with the same experimental setup
because of the existence of other edge states in two dimensions. The proposed
charge transport experiment may provide a simple and experimentally feasible
method for the detection of Majorana fermions in semiconductor nanowires.
