Experimental Investigation of a Cavity-Mode Resonator Using a Micromachined Two-Dimensional Silicon Phononic Crystal in a Square Lattice

Abstract

Abstract-A 2-D silicon phononic crystal (PnC) slab of a square array of cylindrical air holes in a 10-μm-thick freestanding silicon plate with line defects is characterized as a cavity-mode PnC resonator. A piezoelectric aluminum nitride (AlN) film is employed as the interdigital transducers to transmit and detect acoustic waves, thus making the whole microfabrication process CMOS compatible. Both the band structure of the PnC and the transmission spectrum of the proposed PnC resonator are analyzed and optimized using finite-element method. The measured quality factor (Q factor) of the microfabricated PnC resonator is over 1000 at its resonant frequency of 152.46 MHz. The proposed PnC resonator shows promising acoustic resonance characteristics for radio-frequency communications and sensing applications.

Evidence on simultaneous improvement of motional impedance and Q-factor of silicon phononic crystal micromechanical resonators by variously engineering the cavity defects

“…27 The band diagram is calculated by finite elements method described in detail in Ref. 23, by the combination of calculated eigenfrequencies obtained when sweeping the wave vector along the irreducible part of the first Brillouin zone. The optimized band diagram shown in Fig.…”

“…By adding certain defects within the PnC structure, the confinement and control of elastic waves, such as elastic waveguides and mechanical resonators, [17][18][19][20] can be achieved. For example, PnCs with a line defect created can be the basis to form a waveguide 21,22 or a cavity-mode resonator in the form of a Fabry-Perot (FP) cavity structure; [23][24][25] Bloch-mode resonators can be formed by adding an extra row of scattering holes, 26 reducing the central three rows of scattering holes, 27 or introducing alternate defects 28,29 to the FP cavity structure.…”

Integration of RF MEMS resonators and phononic crystals for high frequency applications with frequency-selective heat management and efficient power handling

“…Same slab of AlN is used t array that surrounds the resonator area. ing capability that ipating heat at the bandgap structure, filter [12] Fig. 3).…”

Investigation on the optimized design of alternate-hole-defect for 2D phononic crystal based silicon microresonators

“…[29][30][31][32][33][34][35][36][37][38][39][40][41][42] For example, magnified directional acoustic source can also be created based on the resonant cavity of 2D PnCs 34 ; a waveguide can be realized by adding a line defect (e.g., removing one row of holes) to PnC structure 35 ; point defect modes are created to have high Q resonance on a 2D PnC slab 43 ; cavity-mode resonators can be formed by introducing a line defect in the form of a Fabry-Perot resonant cavity structure. 44,45 However, there is one problem in this kind of cavity-mode resonators, which is known as the mode mismatch between the cavity mode (mode existed in the Fabry-Perot cavity) and the evanescent propagating mode (mode existed in the surrounding PnC). Analogically to the well-known photonic crystals (PhCs), such mode mismatch leads to significant scattering loss and reduction in the Q factor, 46 because abrupt terminations of the resonant cavity scatter the incident energy to other directions instead of reflecting the energy backward.…”