A reconfigurable device includes a first insulating layer, a second insulating layer, and a nanoscale quasi one- or zero-dimensional electron gas region disposed at an interface between the first and second insulating layers. The device is reconfigurable by applying an external electrical field to the electron gas, thereby changing the conductivity of the electron gas region. A method for forming and erasing nanoscale-conducting structures employs tools, such as the tip of a conducting atomic force microscope (AFM), to form local electric fields. The method allows both isolated and continuous conducting features to be formed with a length well below 5 nm.