The acoustic phonon limited mobility of two-dimensional electrons in an (001)AIGaAslGaAs heterojunction is calculated. It exceeds the highest experimentally achieved value of mobility by approximately six times at the liquid helium temperature.

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The non-stationary equation of diffusion in energy space is solved when the initial binding energy of the atom is much smaller than the thermal energy k,T (collisional scattering) or atomic energy (interaction with a microwave field). As the result, analytic expressions for the diffusive ionisation rate of Rydberg atoms are obtained in the regime of their non-stationary generation.

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Formation of bismuth nanocrystals in GaAsBi layers grown by molecular beam epitaxy at 330 °C substrate temperature and post-growth annealed at 750 °C is reported. Superlattices containing alternating 10 nm-thick GaAsBi and AlAs layers were grown on semi-insulating GaAs substrate. AlAs layers have served as diffusion barriers for Bi atoms, and the size of the nanoclusters which nucleated after sample annealing was correlating with the thickness of the bismide layers. Energy-dispersive spectroscopy and Raman scattering measurements have evidenced that the nanoparticles predominantly constituted from Bi atoms. Strong photoluminescence signal with photon wavelengths ranging from 1.3 to 1.7 μm was observed after annealing; its amplitude was scaling-up with the increased number of the GaAsBi layers. The observed photoluminescence band can be due to emission from Bi nanocrystals. The carried out theoretical estimates support the assumption. They show that due to the quantum size effect, the Bi nanoparticles experience a transition to the direct-bandgap semiconducting state.

The momentum relaxation of one-dimensional electrons scattered by acoustic phonons has been investigated in the Bloch-Gr üneisen temperature range. The temperature dependence of mobility follows the same, µ ∝ T −5 (for deformation acoustic interaction) and µ ∝ T −3 (for piezoelectric interaction), power laws as known for two-dimensional and three-dimensional Fermi gases. The calculations performed estimate µ to be ∼10 8 cm 2 V −1 s −1 at T ≈ 1 K and at low electron concentrations. The specific feature of a one-dimensional gas is an intermediate temperature region, where an exponential temperature dependence of mobility is traced.

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The results of photoemission study of icosahedral single-grain ZnMgEr quasicrystals are presented. Synchrotron radiation photoemission measurements were performed on in situ cleaved samples at 10−10 mbar pressure and low, 140–150 K, temperature. The valence band photoemission spectra measured reveal a simple-metal type valence band of i-ZnMgEr with a distinct Fermi edge cutoff and a spectral feature at 0.7 eV below εF. Analysis of the PE spectra shows that the spectral feature observed corresponds to the van Hove singularities in the density of states, which are due to intersections of the Fermi surface with the 222100 and 311111 Bragg planes.