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We show, from self-consistent calculations, that the effective mass for motion of holes along a two-dimensional (111) Ge layer is almost an order of magnitude smaller than the bulk heavy hole mass, which determines the intersubband distances. This creates a unique situation of multiple populated electric subbands at moderate hole densities p_s and layer widths. Depopulation of two or more upper subbands in a 38 nm wide p-Ge layer with p_s=5×10¹⁵m^-2 has been revealed from the magnetoresistance in high parallel magnetic fields, while a collapse of the quantum Hall state for filling factor ν=1 indicates that two ground subbands merge in a self-formed double-quantum-well potential profile. The latter effect in the valence band is shown to be sensitive to the layer deformation.

In this paper, we study the adsorption of Ba on the Ni(110) surface at room temperature. The investigation takes place mainly by soft X-ray photoelectron spectroscopy measurements. At low coverage (<0.5 ML), the Ba adatoms are in a partially ionic state, whereas at higher coverage, the barium overlayer becomes metallic. The nonmetal to metal transition is characterized by a new Ba 4d doublet appearing at higher binding energy. This more bound Ba 4d core state is attributed to initial state changes of the electrostatic potential at the atomic core region, due to changes in the hybridization of the Ba atoms from Ba 5d with Ni 3d, to Ba 5d, 6s and 6p states in the metallic phase. The latter states are more spatially extended than the Ba 5d ones, overlapping with the Ni 3d orbitals in the nonmetal and therefore lead to a reduced potential at the core electrons. A strong effect on the Ba 4d binding energy shifts, due to the surface dipole induced by the adsorbate itself, was observed.

In order to determine its electronic and chemical properties, the Al₂O₃/p-GaN(0001) interface is studied in situ by the X-ray and ultraviolet photoelectron spectroscopies (XPS and UPS). Using physical vapor deposition (PVD) method, the Al₂O₃ film is deposited step by step under ultra-high vacuum (UHV) onto p-GaN(0001) surface covered with residual native Ga oxide. Prior to the first Al₂O₃ layer evaporation, binding energy of the Ga 3$d$ substrate line is equal to 20.5eV. The PVD method of deposition leads to an amorphous Al₂O₃ film formation. For the final 12.0nm thick Al₂O₃ film binding energy of the Al 2$p$ line is set at 76.0eV and for the O 1$s$ line at 532.9eV. The valence band offset (VBO) and the conduction band offset (CBO) of the Al₂O₃/p-GaN(0001) interface are determined to be equal to $-$1.6eV and 1.8eV, respectively.

Nitrogen-doped diamond-like carbon (N-DLC) films were synthesized by plasma immersion ion implantation and deposition (PIII-D) at room temperature (RT). During the process of deposition, N₂ flow was changed from 0 to 10 sccm. Lifshitz–van der Waals/acid–base (LW-AB) approach was employed to study the surface electronic state of the films, X-ray photoelectron spectroscopic (XPS) and valence band spectra (VBS) were used to study chemical bonds and electron structure information inside the films. Bandgap of the films were calculated by the data from ultraviolet spectrophotometer. The results showed that synthesized films were n-type semiconductors and doping of nitrogen element will affect the accepted–electron capability of the film. The change tendency of the bandgap coincides with that of the ratio of acidic to alkaline component of the polar acid-alkali surface energy. There was much sp hybrid electronic state existed in the films, which mainly sp²C=C/C=N and sp³C–C/C–N bonds.

We show, from self-consistent calculations, that the effective mass for motion of holes along a two-dimensional (111) Ge layer is almost an order of magnitude smaller than the bulk heavy hole mass, which determines the intersubband distances. This creates a unique situation of multiple populated electric subbands at moderate hole densities p_s and layer widths. Depopulation of two or more upper subbands in a 38 nm wide p-Ge layer with p_s = 5 × 10¹⁵m⁻² has been revealed from the magnetoresistance in high parallel magnetic fields, while a collapse of the quantum Hall state for filling factor ν = 1 indicates that two ground subbands merge in a self-formed double-quantum-well potential profile. The latter effect in the valence band is shown to be sensitive to the layer deformation.