Maw-Shung Lee

Rayleigh surface acoustic wave modes of interdigital transducer/(100) AlN/(111) diamond

In this research, Rayleigh surface acoustic wave (SAW) modes of interdigital transducer (IDT)/(100) AlN/(111) diamond were theoretically analyzed and exhibited some excellent acoustic properties. Those Rayleigh SAW modes have smaller film thickness ratios (h/λ), higher phase velocities, and larger electromechanical coupling coefficients (K2) than the ones of IDT/(002) AlN/(111) diamond. Especially for mode 1, the phase velocity is 10 474 m/s, the K2 is 2.31%, and the film thickness ratio (h/λ) is 0.3. The research results exhibit that IDT/(100) AlN/(111) diamond has some excellent properties and provides a predictable and theoretical basis for further application in high velocity SAW devices.

Bulk acoustic wave analysis of crystalline plane oriented ZnO films

Bulk acoustic wave (BAW) properties of piezoelectric layer are very important design parameters for film bulk acoustic wave resonator devices. In this research, BAW properties of all crystalline plane oriented sputtered and epitaxial ZnO films were analyzed theoretically. The (002), (004), and (006) oriented ZnO films provided a pure longitudinal mode. The (100), (110), (200), (210), (300), and (220) oriented ZnO films provided a pure fast shear mode. The (101), (102), (103), (112), (201), (202), (104), (203), (211), (114), (212), (105), (204), (213), (302), (205), (106), and (214) oriented ZnO films provided a quasilongitudinal mode and a quasishear mode. Those bulk acoustic wave properties can be used for further device design and application.

Bulk Acoustic Wave Analysis of Crystalline-Plane-Oriented Aluminum Nitride Films

Bulk acoustic wave analysis of all crystalline-plane-oriented AlN films were studied in this research. Different crystalline-plane-oriented AlN films will form different vibration modes and acoustic properties. (002)-, (004)-, and (006)-oriented AlN films provided a pure longitudinal mode. (100)-, (110)-, (200)-, (210)-, and (300)-oriented AlN films provided a pure fast shear mode. (101)-, (102)-, (103)-, (112)-, (201)-, (202)-, (104)-, (203)-, (211)-, (114)-, (212)-, (105)-, (204)-, (213)-, (302)-, (205)-, (106)-, and (214)-oriented AlN films provided a quasi-longitudinal mode and a quasi-shear mode. These bulk acoustic wave properties can be used for further device design and application.

High velocity shear horizontal surface acoustic wave modes of interdigital transducer/(100) AlN/(111) diamond

In this research, shear horizontal (SH) surface acoustic wave (SAW) modes of interdigital transducer (IDT)/(100) AlN/(111) diamond propagated along the y-axis were theoretically analyzed and they exhibited excellent SH SAW properties. This is special for mode 0 where the K2 curve shows a maximum value (1.27%) at h/λ=0.28 and the velocity is 7496 m/s. The research results provide a predictable and theoretical basis for further application on high velocity SH SAW devices.

A Novel Compact Dual-Mode Filter Using Cross-Slotted Patch Resonator for Dual-Band Applications

A novel dual-mode BPF using cross-slotted patch resonator (CSPR) combined with a square etched slot to have dual-band performances is proposed and developed for hybrid and monolithic microwave and millimeter-wave integrated-circuit. Pair of unequal crossed slot is embedded in the center of lambda/4 patch resonator to generate a passband. When the widths of the crossed slots are different, the slots are as the perturbation element to generate two transmission zeros. Meanwhile, a square slot is introduced and tilted at the angle of 45deg within the center of the CSPR to tune the second resonant frequency over a wide frequency range for application in 2.4/5.2 GHz response. The measured result is in good agreement with the full-wave simulation result.

Memory and electrical properties of (100)-oriented AlN thin films prepared by radio frequency magnetron sputtering

The (100)-oriented aluminum nitride (AlN) thin films were well deposited onto p-type Si substrate by radio frequency (RF) magnetron sputtering method. The optimal deposition parameters were the RF power of 350 W, chamber pressure of 9 mTorr, and nitrogen concentration of 50%. Regarding the physical properties, the microstructure of as-deposited (002)- and (100)-oriented AlN thin films were obtained and compared by XRD patterns and TEM images. For electrical properties analysis, we found that the memory windows of (100)-oriented AlN thin films are better than those of (002)-oriented thin films. Besides, the interface and interaction between the silicon and (100)-oriented AlN thin films was serious important problem. Finally, the current transport models of the as-deposited and annealed (100)-oriented AlN thin films were also discussed. From the results, we suggested and investigated that large memory window of the annealed (100)-oriented AlN thin films was induced by many dipoles and large electric field applied.

Propagation Characteristics of Surface Acoustic Waves in AlN/128° Y–X LiNbO3 Structures

In this study, propagation characteristics of surface acoustic waves in a layered piezoelectric structure (AlN/128° Y–X LiNbO3) are investigated. The phase velocity and coupling coefficient of the layered structure with interdigital transducers (IDTs) and/or thin metal films deposited at various interfaces are calculated numerically. The effects of the polarity of 128° Y–X LiNbO3 on SAW characteristics are illustrated. The calculated phase velocity and coupling coefficient of SAWs in the IDT/ZnO/128° Y–X LiNbO3 structure are also demonstrated for comparison. The simulation results obtained in this study can be applied to the design of SAW devices using AlN/128° Y–X LiNbO3 structures.

Surface acoustic wave properties of (100) AIN films on diamond with different IDT positions

(100)AlN films have better surface acoustic wave (SAW) properties than (002) AlN films. In this research, (100) AlN films were combined with diamonds as a new composite SAW substrate. The SAW properties of (100) AlN films on diamonds were analyzed with 4 composite structures: interdigital transducer (IDT)/(100)AlN/diamond, (100)AlN/IDT/diamond, IDT/(100)AlN/metal/diamond, and metal/IDT/(100) AlN/diamond, and they exhibited some excellent SAW properties. Our research results provide a predictable and theoretical basis for further application on high-velocity SAW devices.

Theoretical bulk acoustic wave properties of (103) AlN films

The theoretical bulk acoustic wave properties of (103)-oriented AlN films were studied in this research. The (103)-oriented AlN films provided a quasi longitudinal mode and a quasi fast shear mode. For the quasi longitudinal mode, the acoustic velocity is 10717 m/s and the piezoelectric coupling constant (K2) value is 4%. For the quasi fast shear mode, the acoustic velocity is 5957 m/s and the K2 value is 3.8%.

Rayleigh and shear horizontal surface acoustic properties of (100) ZnO films on silicon

(100) ZnO films on silicon will excite Rayleigh SAWs along the z-axis and shear horizontal (SH) SAWs along the y-axis. Rayleigh SAW modes of (100) ZnO films on silicon have smaller film thickness ratios, higher phase velocities, and larger electromechanical coupling coefficient (K2) than the those of (002) ZnO films on silicon. This is special for Rayleigh mode 1, where the K2 curve shows a maximum value of 3.37% at h/¿ = 0.28 and the velocity is 5258 m/s. This is special for SH mode 0, where the K2 curve shows a maximum value of 3.3% at h/¿ = 0.28 and the velocity is 3242 m/s.