Modification of the Fermi-level pinning of GaAs surfaces through InAs quantum dots

Room-temperature photoreflectance in van Hoof structures together with atom ic force microscopy has been used to determine the influence of InAs quantu m dots on the Fermi-level pinning of {100} GaAs surfaces. We show that quan tum dots with base lengths of 10 and 25 nm lead to the Fermi level being pi nned approximately 250 meV deeper in the band gap, an effect which is rever sible by either overgrowing the dots with GaAs or by selectively etching aw ay the dots. These results are discussed within the framework of recent the oretical investigations of surface states due to polar facets associated wi th quantum dots. [S0163-1829(99)51944-9].