▎ 摘　　要

Based on the transfer-matrix method, we have investigated the coherent quantum transport in a graphene-based normal metal-insulator-superconductor (NG/IG/SG) junctions, in the limit of a thin barrier. It is found that the conductance spectra of such system, in contrast to a pi periodic oscillatory behavior is shown for aligned Fermi surfaces of the normal and superconducting regions, exhibit a new pi/2 periodic oscillatory behavior as a function of barrier strength (chi) for a large Fermi surface mismatch. (C) 2009 Elsevier B.V. All rights reserved.