This project aims at a comprehensive description of organic semiconductor growth on the graphene substrate. Graphene-based variable barrier interface transistors present a promising concept for organic semiconductor devices with several advantages, i.e., high driving current, high-speed operation, flexibility, and scalability while being less demanding for lithography. However, this research requires a multilevel approach, as the substrate determines the growth of the first layers, which, in turn, influences the growth of thin films. We will address all of these: (i) optimize the graphene on SiC in terms of homogeneity, regularity, doping, and smoothness; (ii) describe the growth kinetics of organic semiconductor molecules as a function of temperature, flux, and graphene doping; and (iii) determine structure and morphology of organic semiconductor thin films. We hope to provide a solid knowledge base to utilize grapheneorganic semiconductor hybrid structures in functional devices.