Quantum tunneling in scanning tunneling microscopy superlattices quantum wires and quantum dots
Understanding the atomic and electronic structure of materials, the elctronic properties of surfaces down tot he atomic scale,a nd the behaviour of particle propagation in nanoscale structures has been increasingly emphasized by the rapid advance of science and technology. it has, for many decades, beent he goal of fundamental and applied research to obain informaiton on physical dynamics at the atomic levela nd subsequently to manipulate the structure of materials at such levels to optimize the properties of interest. Whent he spatial dimension of the structure inw hich particles move is reduced to such a scale that is comaprable tot he de Broglie wavelength o the particles the classical or semiclassical picture is inadequate. the tuneling phenomena in scanning tunneling microscopy (STM), nanostructures such as superlatices (SL's), quantum wires (QW's) [6,7], and quantum dots (QD's)  are osme of the most outstandign examples that cannot be udnerstood int he framework of classical or semiclassical theories. Teh research presented int his thesis has been focussed on developing theoretical methods to find solutions to some of the unsolved problems which have arised from recent experiemnts. Teh problems discussed in this thesis include: * the imaging mechanism in scanning tunneling microscopy; * the transmission property of superlattices; * the origin o the quantized conductance int he quantum wires; and * the interpretaiton of periodic conductance oscillations in quantum dots.
it will be seen that quantum tunneling plays an improtant role inall the above problems.