A
two-dimensional electron gas (2DEG) is a
scientific model in
solid-state physics. It is a
electron gas that is free to move in two dimensions, but tightly confined in the third. This tight confinement leads to quantized
energy levels for motion in the third direction, which can then be ignored for most problems. Thus the electrons appear to be a 2D sheet embedded in a 3D world. The analogous construct of
holes is called a two-dimensional hole gas (2DHG), and such systems have many useful and interesting properties.