Low temperature scanning tunneling spectroscopy on InAs(110)

We review our recent work on low temperature scanning tunneling spectroscop y (STS) in magnetic field on InAs(110). First, we describe the influence of the tip on the sample. It results in band bending at the InAs-surface, mor e precisely in a so called tip induced quantum dot. STS of the quantum dot states is used to reconstruct the quantum dot potential, a major requiremen t for all further measurements. Second, we analyze the appearance of ionize d dopants in constant current images within a simple model based on the loc al band bending approach. Third, we show scattering states of ionized dopan ts at different energies appearing in normalized dI/dU-images. Comparison w ith calculated scattering states in the Wentzel-Kramers-Brillouin (WKB)-app roximation gives good correspondance and a good estimate of the depth of in dividual dopants beneath the surface. Finally, we discuss the energy quanti zation of the unoccupied states of the tip induced quantum dot in magnetic field. The corresponding dI/dU-curves exhibit peaks attributed to the Landa u quantization and the spin splitting of the quantum dot. (C) 2000 Elsevier Science B.V. All rights reserved.