SHAPE EFFECTS ON CONDUCTANCE QUANTIZATION IN 3-DIMENSIONAL NANOWIRES - HARD VERSUS SOFT POTENTIALS

Effects of the shapes of the cross sections of three-dimensional nanow ires on electronic conductance quantization are studied for both hard- and soft-wall potentials. In both models the quantum conductance is d etermined by both the area and shape of the narrowmost part of the nan owire. For the hard-wall potential the semiclassical (Weyl) correction to the Sharvin formula provides an adequate approximation to the aver age quantized conductance. For nanowires modeled by soft-wall potentia ls, the average quantum conductance may be well estimated using a clas sical approximation.