Defect engineering of silicon based 2-D phononic crystals

Abstract

This work reports the numerical and experimental study on the micromechanical resonators which are made by engineering various types of defects on an otherwise perfect two-dimensional (2-D) PnC slab. The 2-D PnC slab is made by etching a square array of cylindrical air holes in a free-standing silicon plate with thickness of 10?m, whereas the defects which are engineered include pure Fabry-Perot resonant cavity, one row of additional air holes introduced in the Fabry-Perot resonant cavity, central rows of air holes with reduced radii, as well as alternate defects whichare formed by alternately removing the central rows of air holes. For each type of defects, devices with different cavity lengths and different central-hole radii are fabricated using an in-house CMOS compatible process. Testing is done to characterize the resonant frequency, the quality factor,and insertion loss of the devices and the results agree with FEM data very well.