Showing papers on "Quantum dot published in 1985"

Effects of quantum confinement in a special GaAs field effect transistor: on the DC conductance in the regime of metallic transport

Abstract: The DC electrical transport properties of the conducting channel of GaAs field effect transistors are studied theoretically and experimentally in the regime of metallic conduction. Because the electron motion perpendicular to the channel is restricted to a potential well a sub-band structure develops. The thickness t of the channel can be varied over a wide range by the gate bias. The sub-band structure and the dependence of the fermi energy Ef on t has been calculated and compared with previous experimental values. The DC conductance has been studied within the framework of the Boltzmann transport equation. The scatterers are taken as dielectrically screened point charges. Because of the sub-band structure the transport times have to be determined from a set of coupled Boltzmann equations. In the elementary approximation used here, the Boltzmann transport equation predicts pronounced quantum size effects (QSE) associated with sub-band structure. In order to test the predictions of the present theory measurements have been performed at 4.6K. The devices used were not of the conventional design in order to ensure that the conducting channel was in the region of constant doping. The role of impurity scattering and associated broadening effects are briefly discussed.

Quantum well wires: electrical and optical properties

Abstract: Quantum theoretical results on electrical and optical properties of quantum well wires (QWW) are described under strong quantum confinement conditions when acoustic phonon, point defect or alloy scattering is enhanced, and ionised-impurity scattering is suppressed. A quantum size resonance is expected to take place when the energy of a photon polarised perpendicular to the wire is equal to the spacing between the quantised energy levels. The linewidth is shown to be proportional to ( lambda D2/A) tau b, where lambda D is the de Broglie wavelength of an electron. A is the confinement area, and tau b is the bulk relaxation time. A quantum freeze-out of confined carriers is expected to induce a semimetal-semiconductor transition in semimetallic thin wires.