Quantum ballistic transport through a double-bend waveguide structure: Effects of disorder

We investigate the quantum transport properties through a variety of double-bend electron-waveguide structures using the recursive Greens-function technique. The conductance is calculated as a function of the chemical potential using the two-probe multichannel Landauer-Büttiker formula. Detailed numerical calculations are presented to study the effects of waveguide geometry, impurity scattering, interface roughness, and finite temperature on the quantum conduction. We find that the roundness of the corners washes out the resonance structure by increasing the conductance in the valley regions. Impurity scattering and interface roughness slightly shift the peak positions and decrease their amplitudes. Thermal averaging of the conductance leads to a broadening of the resonance peaks, and a corresponding decrease of the peak amplitudes.