GUIDED AND INTERFACE LO PHONONS IN CYLINDRICAL GAAS/ALXGA1-XAS QUANTUM WIRES

A dispersive hydrodynamic continuum theory is employed to describe the LO phonons in GaAs/AlxGa1-xAs cylindrical quantum wires. It is demonstrated that a finite number of guided modes exist for a given wire radius, their number being greater than the corresponding slab system due to the reduced symmetry. As for the interface modes, it is shown that a given mode occurs at a critical wave vector, although the axially symmetric mode always exists, it having zero critical wave vector. The situation is drastically modified in the case of a free-standing wire. Within the continuum model and with physically plausible boundary conditions, guided modes exist whereas interface modes do not. Implications for electron transport are discussed. © 1990 The American Physical Society.