EFFECTS OF COMPOSITIONAL IMPURITIES AND WIDTH VARIATION ON THE CONDUCTANCE OF A QUANTUM-WIRE

An exact single-particle scattering theory formulation of the problem of elastic electronic transport is employed in a Is tight-binding impl ementation to study the zero-voltage, zero-temperature conductance of a two-dimensional quantum wire as a function of the Fermi energy. For a perfect wire, the conductance quantization effect is reproduced. The n, the effects on the conductance of compositional impurities and widt h variation in the wire are studied. It is found that the quantization effect is seriously damaged even with minimal amounts of impurity, wh ereas it exhibits some tolerance towards width variation, especially a t low carrier concentrations. It is found that with both types of diso rder the conductance is particularly strongly suppressed at Fermi ener gies close to the edges of the subbands for the perfect wire, which, i n agreement with previous findings, shows that at those energies the l ocalization of the electrons by the disorder is enhanced.