Physics of band-gap formation and its evolution in the pillar-based phononic crystal structures

Articles you may be interested in Experimental evidence of high-frequency complete elastic bandgap in pillar-based phononic slabs Appl. Superlensing effect for surface acoustic waves in a pillar-based phononic crystal with negative refractive index Appl. Finite element analysis and experimental study of surface acoustic wave propagation through two-dimensional pillar-based surface phononic crystal Extending of band gaps in silicon based one-dimensional phononic crystal strips Appl. Low-frequency locally resonant band-gaps in phononic crystal plates with periodic spiral resonators In this paper, the interplay of Bragg scattering and local resonance is theoretically studied in a phononic crystal (PnC) structure composed of a silicon membrane with periodic tungsten pillars. The comparison of phononic band gaps (PnBGs) in three different lattice types (i.e., square, triangular, and honeycomb) with different pillar geometries shows that different PnBGs have varying degrees of dependency on the lattice symmetry based on the interplay of the local resonances and the Bragg effect. The details of this interplay is discussed. The significance of locally resonating pillars, specially in the case of tall pillars, on PnBGs is discussed and verified by examining the PnBG position and width in perturbed lattices via Monte Carlo simulations. It is shown that the PnBGs caused by the local resonance of the pillars are more resilient to the lattice perturbations than those caused by Bragg scattering. V C 2014 AIP Publishing LLC.