physica status solidi (a)

Electronic correlation and electron-phonon coupling are enhanced by low dimensionality. Two-dimensional systems can be easily found in surfaces and interfaces. Among all surfaces semiconducting surfaces are particularly well adapted for electronic correlation studies. Electron localization is high in dangling bonds, often widely spaced. In this Feature Article the authors review the discovery of correlated surfaces and focus on K/Si(111):B and Sn/Ge(111). On K/Si(111) they discuss the role of correlation and the importance of electron-phonon coupling. On Sn/Ge(111) they present that its surface Mott transition is driven by temperature.