Method of forming a semiconductor device structure and semiconductor device structure

A semiconductor device structure includes a hybrid substrate having a semiconductor-on-insulator (SOI) region that includes an active semiconductor layer, a substrate material and a buried insulating material interposed between the active semiconductor layer and the substrate material, and a bulk semiconductor region that includes the substrate material. An insulating structure is positioned in the hybrid substrate, wherein the insulating structure separates the bulk region from the SOI region, and a gate electrode is positioned above the substrate material in the bulk region, wherein the insulating structure is in contact with two opposing sidewalls of the gate electrode.