Jr. Shi et By. Gu, QUANTUM WAVE-GUIDE TRANSPORT WITH SIDE-BRANCH STRUCTURES - A RECURSIVE ALGORITHM, Physical review. B, Condensed matter, 55(7), 1997, pp. 4703-4709
Electronic conductance of a quantum waveguide with side-branch structu
res is investigated. We introduce impedance factors for geometric and
potential scatterers and develop a recursive algorithm. impedance fact
ors for several basic unit structures, recursion formulas, and an addi
tion rule are presented with the use of one-dimensional quantum wavegu
ide theory. The impedance factor of a complicated side-branch structur
e can be evaluated from impedance factors of the individual parts cont
ained in the structure as in the classical resistance-network calculat
ion. This method makes conductance calculations simple since the wave
functions of the structures are not required. With this method conduct
ance properties of the quantum waveguides with different periodic side
-branch structures (vertical structures) are studied in detail. Electr
onic conductance of these side-branch modulators manifests band struct
ure with fast oscillating regions and inherent regions. As the number
of repeat structures increases, the number of sharp peaks in the oscil
lating bands increases proportionally while the conductance profiles i
n the inherent bands remain unchanged. Comparison with the conductance
of similar periodic structures along the main wire (horizontal struct
ures) reveals that the oscillating bands and inherent bands of the ver
tical structure correspond to the transmission bands and forbidden ban
ds of the horizontal structure, respectively.