A nanoscale three-terminal switching device has a bottom electrode, a top electrode, and a side electrode, each of which may be a nanowire. The top electrode extends at an angle with respect to the bottom electrode and has an end section going over and overlapping the bottom electrode. An active region is disposed between the top electrode and bottom electrode and contains a switching material. The side electrode is disposed opposite from the top electrode and in electrical contact with the active region. A self-aligned fabrication process may be used to automatically align the formation of the top and side electrodes with respect to the bottom electrode.