High Frequency Surface Acoustic Wave Filter Using ZnO/Diamond/Si Structure

Abstract

In the slow-roll inflationary scenario, the amplitude of the curvature perturbations approaches a constant value soon after the modes leave the Hubble radius. However, relatively recently, it was shown that the amplitude of the curvature perturbations induced by the canonical scalar field can grow at super-Hubble scales if there is either a transition to fast roll inflation or if inflation is interrupted for some period of time. In this work, we extend the earlier analysis to the case of a non-canonical scalar field described by the Dirac-Born-Infeld action. With the help of a specific example, we show that the amplitude of the tachyonic perturbations can be enhanced or suppressed at super-Hubble scales if there is a transition from slow roll to fast roll inflation. We also illustrate as to how the growth of the entropy perturbations during the fast roll regime proves to be responsible for the change in the amplitude of the curvature perturbations at super-Hubble scales. Furthermore, following the earlier analysis for the canonical scalar field, we show that the power spectrum evaluated in the long wavelength approximation matches the exact power spectrum obtained numerically very well. Finally, we briefly comment on an application of this phenomenon.

Characterization of acoustic Lamb wave propagation in polycrystalline diamond films by laser ultrasonics

“…Experimentally, high frequency SAW velocities of up to 10 000 ms Ϫ1 have previously been measured in ZnO-polycrystalline CVD diamond layered structures. 8 The high values recorded here for samples 6 and 7 are, within the experimental errors, close to the expected Rayleigh velocities for single crystal diamond. Apart from sample 2, all other films support waves with a FIG .…”

“…6 Nakahata and co-workers have reported promising filter performance characteristics from ZnO-diamond multilayered SAW structures. [7][8][9] The chemically inert nature of diamond; its high strength and relatively low density allied to a high thermal conductivity suggest it as an ideal substrate for sensing applications in hostile environments; the use of diamond for FPW sensor structures has not been previously addressed. The design of both SAW and FPW devices requires knowledge of the acoustic properties of the substrate.…”

Deposition of Aluminium Nitride Film by Magnetron Sputtering for Diamond-Based Surface Acoustic Wave Applications

“…The centre frequency of the AlN/ diamond filter is twice the AlN/Si frequency. The calculated Rayleigh-like mode wave velocity of the diamond filter (v ¼ 9980 m s À1 ) is higher than the values reported on zinc oxide/diamond filters [10,11]. The insertion loss of these two filters is high and the suppression is low for the diamond devices.…”

Filtering performance improvement in V-doped ZnO/diamond surface acoustic wave filters

“…The rapid development of high-speed and large-volume communication systems has increased the demand of high-frequency filters with low-loss and high electromechanical coupling coefficient K 2 [3,4]. The high-frequency devices can be obtained by employing the piezoelectric films/diamond layered structures because diamond exhibits the highest acoustic wave velocity among all materials [5].…”