Low-temperature electrical conductance spectroscopy measurements of quantum point contacts implemented in p-type GaAs/AlGaAs heterostructures are used to study the Zeeman splitting of 1D subbands for both in-plane and out-of-plane magnetic field orie
ntations. The resulting in-plane g-factors agree qualitatively with those of previous experiments on quantum wires while the quantitative differences can be understood in terms of the enhanced quasi-1D confinement anisotropy. The influence of confinement potential on the anisotropy is discussed and an estimate for the out-of-plane g-factor is obtained which, in contrast to previous experiments, is closer to the theoretical prediction.
A nano-fabrication technique is presented which enables the fabrication of highly tunable devices on p-type, C-doped GaAs/AlGaAs heterostructures containing shallow two-dimensional hole systems. The high tunability of these structures is provided by
the complementary electrostatic effects of intrinsic in-plane gates and evaporated metallic top-gates. Quantum point contacts fabricated with this technique were tested by electrical conductance spectroscopy.
Quantum point contacts implemented in p-type GaAs/AlGaAs heterostructures are investigated by low-temperature electrical conductance spectroscopy measurements. Besides one-dimensional conductance quantization in units of $2e^{2}/h$ a pronounced extra
plateau is found at about $0.7(2e^{2}/h)$ which possesses the characteristic properties of the so-called 0.7 anomaly known from experiments with n-type samples. The evolution of the 0.7 plateau in high perpendicular magnetic field reveals the existence of a quasi-localized state and supports the explanation of the 0.7 anomaly based on self-consistent charge localization. These observations are robust when lateral electrical fields are applied which shift the relative position of the electron wavefunction in the quantum point contact, testifying to the intrinsic nature of the underlying physics.
A quantum dot fabricated by scanning probe oxidation lithography on a p-type, C-doped GaAs/AlGaAs heterostructure is investigated by low temperature electrical conductance measurements. Clear Coulomb blockade oscillations are observed and analyzed in
terms of sequential tunneling through the single-particle levels of the dot at T_hole = 185 mK. The charging energies as large as 2 meV evaluated from Coulomb diamond measurements together with the well resolved single-hole excited state lines in the charge stability diagram indicate that the dot is operated with a small number of confined particles close to the ultimate single-hole regime.
