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Two-dimensional electron gases (2DEGs) at surfaces and interfaces of semiconductors are described straightforwardly with a one-dimensional (1D) self-consistent Poisson-Schrödinger scheme. However, their band energies have not been modeled correctly in this way. Using angle-resolved photoelectron spectroscopy we study the band structures of 2DEGs formed at sulfur-passivated surfaces of InAs(001) as a model system. Electronic properties of these surfaces are tuned by changing the S coverage, while keeping a high-quality interface, free of defects and with a constant doping density. In contrast to earlier studies we show that the Poisson-Schrödinger scheme predicts the 2DEG band energies correctly but it is indispensable to take into account the existence of the physical surface. The surface substantially influences the band energies beyond simple electrostatics, by setting nontrivial boundary conditions for 2DEG wave functions. [ABSTRACT FROM AUTHOR]

[Display omitted] • 2DEG at InAs surfaces is described with the Poisson-Schroedinger model. • Surface is important and it have to be accounted for the model. • IBA treatment may lead to the loss of the 2D character of the surface electron gas. Using angle-resolved photoelectron spectroscopy we study band structures of two dimensional electron gases (2DEGs) formed at surfaces of InAs(001) due to the band bending effect. We find that, for surfaces prepared by nondestructive methods very clear, model 2DEG bands are obtained. In contrast, for ion bombarded surfaces features looking as if 2DEG band contours were uniformly filled with signal are seen. We show that these observations may be explained within the one-electron Poisson-Schrödinger scheme, however, it is necessary to relax the standard boundary conditions with adding a transition zone in which the crystal potential may interpolate between its vacuum and bulk values in nontrivial way. In reality such a zones do exist and correspond to non zero thick surface/interface layers. For ion bombarded surfaces it is also necessary to take into account diffusion and complex reactions of point defects induced with an ion beam. These observations are discussed in the context of electronics devices that often contain similar 2DEGs. [ABSTRACT FROM AUTHOR]