The nonpolymeric organic compound rhodamine-101 (Rh101) film on a n-type Si or p-type Si substrate has been formed by means of the evaporation process and the Sn/rhodamine-101/Si contacts have been fabricated. The Sn/Rh101/n-Si and Sn/Rh101/p-Si contacts have rectifying contact behavior with the barrier height (BH) values of 0.714 and 0.827 eV, and with ideality factor values of 2.720 and 2.783 obtained from their forward bias current-voltage (I-V) characteristics at room temperature, respectively. It has been seen that the BH value of 0.827 eV obtained for the Sn/Rh101/p-Si contact is significantly larger than BH values of the conventional Sn/p-Si Schottky diodes and metal/interfacial layer/Si contacts. Thus, modification of the interfacial potential barrier for metal/Si diodes has been achieved using a thin interlayer of the Rh101 organic semiconductor; this has been ascribed to the fact that the Rh101 interlayer increases the effective barrier height by influencing the space charge region of Si. (c) 2006 American Institute of Physics.