An electro-optic modulation component is provided, in particular on an SOI (semiconductor-on-insulator) substrate, improved for better performance at data rates above 10 Gb/s. This improvement is obtained by reducing the influence of the capacitive effects of the structure and of its environment, and more particularly in which the influence of the capacitance of the structure itself is limited by reducing the access resistance in the doped regions or the influence of the capacitive effect of the environment is reduced by modifying the structure of the substrate vertically beneath the active region, for example by thinning the silicon substrate or the insulator, or a combination of these features. The invention furthermore relates to a process for fabricating such a component and to a device or system that includes such a component. These improvements are applicable in 3D integration assembly processes and to electronic and optical hybrid circuits.