We examine the quantum-mechanical transmission in real ssT-shape quantum interference resonator, with two basic types of disorder; impurities and rough boundaries. This system is interesting as a potential quantum transistor. The elastic scattering due to disorder, in general, decreases the conductance in comparison to the perfect system. However, we find that this behavior can be avoided in the single-mode regime, and the transmission could be even enhanced by the presence of repulse impurity potential or boundary roughness. Attractive impurities, on the other hand, suppress the first transmission peak and move the resonances lower in energy. The modulation of the transmission as electron energy is varied is almost 100% irrespective of disorder, except for a range of attractive impurity potentials and if the stub length is not too large. Modulation due to the stub length variations depends on the electron energy and remains very strong if energies are not low. Therefore, the transistor switching function could be preserved in the single-mode regime even for the disordered samples.

• Received 25 April 1995

DOI:https://doi.org/10.1103/PhysRevB.52.9007