2deg

1. Surface two dimensional electrons

1. 2DEG system localized at solid surfaces

(Fig. 1)

(Fig. 2)

On solid surfaces, a two dimentional electron state which is localized at surfaces emerges (Fig. 1).
Since this surface localized electron such as on Ag(111) surfaces can move freely, it is an ideal 2 dimentional electron gas (2DEG) .
The surface electrons is scattered at steps and dislocations at surfaces, then the electron standing waves are appeared (Fig. 2).
The surface electron standing waves can be observed by scanning tunneling microscope (STM) as square of the wave functions (|φ(x, y)|²) (Fig. 2).

Reference: K. Sawa, Y. Aoki, and H. Hirayama, Phys. Rev. B, 80, 035428 (2009).