Metals with considerable work-function difference namely aluminum (Al) and gold (Au) are evaporated on molecularly modified silicon surfaces to form Al-molecules-Si and Au-molecules-Si junctions and the sensitivity of junction barrier to the metal work-function is studied Plots of current-voltage measurements for Al-molecules-Si junctions are Schottky in nature and for Au-molecules-Si junctions there is a transition from ohmic to Schottky behavior with increase in the dipole moment of interfaced molecules This variation along with temperature dependent changes of charge transport properties of molecular junctions is analyzed and discussed (C) 2010 Elsevier B V All rights reserved