Studies of magnetotunneling into donor states and of the breakdown of the quantum Hall effectTools Dickinson, Laurie Alan (2004) Studies of magnetotunneling into donor states and of the breakdown of the quantum Hall effect. PhD thesis, University of Nottingham.
AbstractThis thesis describes an experimental investigation and analysis of two topical problems in condensed matter physics: 1.) the effect of a magnetic field on quantum states of an electron bound to a shallow donor impurity in a quantum well heterostructure and 2.) the breakdown of the quasidissipationless state of the integer quantum Hall effect. Two introductory chapters describe important material parameters and the experimental equipment and techniques used. Magnetotunneling spectroscopy (MTS) is used to probe the spatial form of the eigenfunction of electrons bound in the ground state of a shallow Sidonor impurities in a GaAs/(A1Ga)As quantum well. An inplane magnetic field, B[subscript] , acts to tune the kvector of the tunnelling electron through the effect of the Lorentz force. The variation with B [subscript]  of the tunnel current through the donor ground state provides a map of the Fourier transform, ψ(k) [superscript]2, of the probability density of the ground state donor wavefunction in real space. By applying a strong magnetic field component, B [subscript] , parallel to the direction of tunnel current, it is possible to magnetocompress the donor function in real space. The magnetocompression is investigated using MTS and the data are analysed in terms of a simple model, which is critically discussed.
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