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The accumulation capacitance oscillations behavior in the n-InAs metal-oxide-semiconductor structures with different densities of the built-in charge (Dbc) and the interface traps (Dit) at temperature 4.2 K in the magnetic field (B) 2–10 T, directed perpendicular to the semiconductor-dielectric interface, is studied. A decrease in the oscillation frequency and an increase in the capacitance oscillation amplitude are observed with the increase in B. At the same time, for a certain surface accumulation band bending, the influence of the Rashba effect, which is expressed in the oscillations decay and breakdown, is traced. The experimental capacitance-voltage curves are in a good agreement with the numeric simulation results of the self-consistent solution of Schrödinger and Poisson equations in the magnetic field, taking into account the quantization, nonparabolicity of dispersion law, and Fermi-Dirac electron statistics, with the allowance for the Rashba effect. The Landau quantum level broadening in a two-dimensional electron gas (Lorentzian-shaped density of states), due to the electron scattering mechanism, linearly depends on the magnetic field. The correlation between the interface electronic properties and the characteristic scattering times was established. [ABSTRACT FROM AUTHOR]

The conductance of a single GaAs quantum point contact (QPC) with in-plane side gates separated from a channel by lithographic trenches is experimentally studied. It is shown that, in such a trench-type QPC, the conducting channel splits into two channels, each demonstrating a conductance quantization. A phase diagram of the 1D subband population in separate channels as a function of the voltages at side gates is experimentally obtained. The obtained data show that the electron transport regime undergoes the transition from the case of two independent parallel 1D conductors to the case of strongly correlated double-row transport. The transition occurs with the increase in the number of populated 1D subbands in the channels and manifests itself in the phase diagram by the change of behavior of the lines separating the regions corresponding to different numbers. The crossings of these lines at small numbers turn into anticrossings at large numbers. The anticrossings are explained by the splitting of degenerate levels in a double-well confinement potential formed inside the QPC constriction. [ABSTRACT FROM AUTHOR]

The experimental study of the suspended GaAs quantum point contact (QPC) equipped with in-plane side gates reveals that, under such conditions, the QPC constriction has an unusual triple-channel structure involving three conductive channels with the quantized conductance selectively driven by the gates. The analysis of capacitance coefficients and channel widths allows us to conclude that the channels are narrow, compared to the lithographic constriction of the QPC, and that two of the channels are located along the constriction edges, while the other one passes along the middle line. The suspended QPC with the selectively driven triple-channel structure represents a device with an enhanced functionality. The electrostatic mechanism of the channel formation, specific for trench-type suspended QPCs with side gates, is discussed. [ABSTRACT FROM AUTHOR]

We study electron transport in suspended semiconductor microstructures fabricated from AlAs/GaAs membranes containing a high mobility two-dimensional electron gas. In quantizing magnetic fields, a reflection of edge current channels from the border of suspended area is observed resulting in the absence of vanishing magnetoresistance in the quantum Hall effect (QHE) regime. Relocation of this border out of the Hall bar revives the QHE. We have also found that the critical current of the breakdown of QHE in suspended samples is three times lower than in non-suspended samples due to the peculiarity of heat transport in the membranes. [ABSTRACT FROM AUTHOR]

The conductance of a GaAs-based suspended quantum point contact (QPC) equipped with lateral side gates has been experimentally studied in the absence of the external magnetic field. The half-integer conductance plateau ( 0.5 × 2 e 2 / h ) has been observed when an asymmetric voltage between the side gates is applied. The appearance of this plateau has been attributed to the spin degeneracy lifting caused by the spin-orbit coupling associated with the lateral electric field in the asymmetrically biased QPC. We have experimentally demonstrated that, despite the relatively small g-factor in GaAs, the observation of the spin polarization in the GaAs-based QPC became possible after the suspension due to the enhancement of the electron-electron interaction and the effect of the electric field guiding. These features are caused by a partial confinement of the electric field lines within a suspended semiconductor layer with a high dielectric constant. [ABSTRACT FROM AUTHOR]