A process for obtaining a hybrid substrate that includes at least one active layer of Group III/N material for applications in the field of electronics, optics, photovoltaics or optoelectronics. The method includes selecting a source substrate of Group III/N material having a hexagonal single crystal crystallographic structure; carrying out an implantation of He+ helium ions into the source substrate through an implantation face which lies in a plane approximately parallel with the “c” crystallographic axis of the material, at an implantation dose equal to or greater than 1×1016 He+/cm2 and 1×1017 He+/cm2, to form therein a number of nanocavities defining a weakened zone which delimits the active layer; and transferring the active layer by applying an overall energy budget capable of causing detachment of the layer from the source substrate, wherein the budget also causes the nanocavities to grow into cavities.