In the present work, we report fabrication and current-voltage characteristics of ZnO/alpha-NPD:F-4-TCNQ based inorganic-organic hybrid junction. Current-voltage characteristics of hybrid junctions show diode like behavior. The effect of organic layer doping on the diode like characteristics of the junction has been investigated. The diode parameters viz. barrier height, ideality factor and rectification ratio have been calculated from the current-voltage semi-log plots. The improvement of diode parameters i.e. increase in rectification ratio and decrease in barrier height as well as improvement in ideality factor has been observed with doping. The improvement of the diode parameters has been attributed to the modification at ZnO/alpha-NPD interface. The current is also found to increase with the increase in doping concentration which has been attributed to the increased conductivity of alpha-NPD and interface barrier lowering after doping of alpha-NPD with F-4-TCNQ. (C) 2010 Elsevier B.V. All rights reserved.