Quantum Effects in the Conductivity of a Quasi 2D Electron Gas

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We consider the role of the third dimension in the conductivity of a quasi 2D electron gas. If the transverse correlation radius of the scattering potential is smaller than the width of the channel, i.e. the width of the transverse electron density distribution, then scattering to higher levels of the confinement potential becomes important, which causes a broadening of the current flow profile. The resulting conductivity is larger than that obtained from a 2D Boltzmann equation. A magnetic field, parallel to the driving electric field, effectively competes with the confining potential and, in the limit of a strong magnetic field, it is the field, which largely shapes the electron and current profile, rather than the potential. As a result the current flow profile increases and a negative longitudinal magnetoresistivity of the quasi 2D electron gas may be observed.