Interestingly, the charge transfer and the formation of a two-dimensional electron gas (2DEG) occur only at the interface, unlike in the 3D LaAlO 3 /SrTiO 3 system, where the 2DEG extends beyond ...

A small piece of sodium metal is placed in a flask of chlorine gas ... by sodium. An electron is transferred from sodium to chlorine. Sodium becomes a positive ion and chlorine becomes a negative ion.