Low temperature scanning tunneling spectroscopy on InAs(110)

We review our recent work on low temperature scanning tunneling spectroscopy (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, more 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 requirement for all further measurements. Second, we analyze the appearance of ionized dopants in constant current images within a simple model based on the local band bending approach. Third, we show scattering states of ionized dopants at different energies appearing in normalized dI/dU-images. Comparison with calculated scattering states in the Wentzel-Kramers-Brillouin (WKB)-approximation gives good correspondence and a good estimate of the depth of individual dopants beneath the surface. Finally, we discuss the energy quantization of the unoccupied states of the tip induced quantum dot in magnetic field. The corresponding dI/dU-curves exhibit peaks attributed to the Landau quantization and the spin splitting of the quantum dot.