Laterally patterned two-dimensional electron gases have been fabricated by overgrowth of locally implantation doped Al0.33Ga0.67As barriers. The heterostructures were grown by molecular beam epitaxy and the local doping was performed by focused ion beam implantation. Submicrometer patterning capability was found when testing the insulation behavior of doping interruptions between two conducting rectangles. For a narrow conducting wire, an electronic width of approximately 350 nm was realized. The experiments show that the thermal processing necessary to remove the implantation damage might hamper the lateral resolution and has to be optimized. (c) 2006 American Vacuum Society.