We report on the direct observation by low-temperature scanning tunneling microscopy and scanning tunneling spectroscopy of the d orbitals of a Mn p-type impurity appearing on a cleaved InAs(110) surface. We show that the crucial interplay between nonequilibrium charging effects and many-particle interaction leading to Coulomb singularities provides a consistent description of the experimental results.

We analyze the quantized states of the tip-induced quantum dot appearing in scanning tunneling spectroscopy (STS) on n-type InAs(110) (ND=2×1016 cm-3). STS at negative sample bias (-200–0 mV) is used to determine the state energies. The analysis of the spectra indicates that the z-quantization leads to one or two quantized states while a ladder of states due to the lateral confinement is observed. The magnetic-field dependence (0–6 T) shows the expected splitting of the first excited state in quantitative agreement with Hartree calculations. If an ionized dopant is located in the center of the quantum dot, a reduction in energy and a change in intensity of the single-particle ground state is found, which is also in quantitative agreement with Hartree calculations. The analysis of the tip-induced states can be used to reconstruct the shape of the tip-induced band bending.

hole more localized close to QD top, above e-

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The tip artifact in atomic force microscopy (AFM) observations of InAs islands was evaluated quantitatively. The islands were grown in the Stranski�Krastanow mode of molecular beam epitaxy. The width and height of the islands were determined using transmission electron microscopy (TEM) and AFM. The average [[overline 1]10] in-plane width and height determined using TEM excluding native oxide were 22 and 7 nm, respectively; those determined using AFM including the oxide were 35 and 8 nm, respectively. The difference in width was due to the oxide and the tip artifact. The sizes including the oxide were deduced from TEM observations to be a width of 27 nm and a height of 6 nm with correction for the thickness of the oxide. The residual difference of 8 nm between the width determined using AFM and that determined using TEM including the oxide was ascribed to the tip artifact. The results enable us to determine the actual size of the islands from their AFM images.