Origin of nanoscale potential fluctuations in two-dimensional semiconductors

We demonstrate a direct atomically resolved visualization and quantification of the impact of inhomogeneities in the dopant distribution on the nanoscale potential fluctuations in a two-dimensional semiconducting root 3 x root 3 Ga overlayer on Si(111) using scanning tunneling microscopy. By a quantitative analysis, two regimes of the potential at nanometer scale are found, which arise from the local distribution of charge carriers in the bands and from electron-electron interactions. (C) 2009 American Institute of Physics. [DOI:10.1063/1.3177329