The AFM(atomic force microscope) tip is used to pattern the surface of a GaAs heterostructure by applying a negative Voltage to the tip while moving over the surface . The waterfilm which is always present at ambient conditions leads to local anodic oxidation which is in its effect equivalent to a shallow removal of the topmost surface layer. The "etching" of the surface raises the conduction band at these locations an leads to the depletion of the 2DEG (two dimensional electron gas) 34nm below the surface. This method is then used to write insulating lines as part of quantum wires, quantum point contacts, quantum latices, quantum dots and quantum rings.