Thin films piezoelectric properties

The nonlinear optical and dielectric properties of polymers find increasing use in devices, such as cladding and coatings for optical fibres, piezoelectric and optical fibre sensors, frequency doublers, and thin films for integrated optics applications. It is therefore important to understand the dielectric, optical and mechanical response of polymeric materials to optimize their usage. The parameters that are important to evaluate these properties of polymers are their dipole moment polarizability a, hyperpolarizabilities 0... 

The quartz oscillator coating thickness gauge (thin film controller) utilizes the piezoelectric sensitivity of a quartz oscillator (monitor crystal) to the supplied mass. This property is utilized to monitor the coating rate and final thickness during vacuum coating. 

Far more frequently, however, measurements are made with a relatively thin film (often < 5 /rm) on a comparatively massive substrate (often > 400 //,m in thickness). In principle, the piezoelectric and electromechanical properties of the films can be extracted by fitting conventional resonance measurements. In practice, multiple resonances due to the film/substrate system are measured it is then necessary to deconvolute the data in order to extract information on the films itself. In practice, this is difficult to do unambiguously [21,22],... 

Figure 10.2. Experimental set-up used to study the elastic properties of thin films by RUS. The resonance frequencies are measured with the piezoelectric tripod. The scanning laser-Doppler interferometer draws the oscillation displacement of specimen surface. (Reproduced with permission of Elsevier, Ref. [22].)...

Rende, D. Schwarz, K. Rabe, U. Maier, W. F. Arnold, W., Combinatorial synthesis of thin mixed oxide films and automated study of their piezoelectric properties, Prog. Solid State Chem. 2004, 223, 245-248... 

Surface acoustic waves (SAW), which are sensitive to surface changes, are especially sensitive to mass loading and theoretically orders of magnitude more sensitive than bulk acoustic waves [43]. Adsorption of gas onto the device surface causes a perturbation in the propagation velocity of the surface acoustic wave, this effect can be used to observe very small changes in mass density of 10 g/cm (the film has to be deposited on a piezoelectric substrate). SAW device can be useful as sensors for vapour or solution species and as monitors for thin film properties such as diffusivity. They can be used for example as a mass sensor or microbalance to determine the adsorption isotherms of small thin film samples (only 0.2 cm of sample are required in the cell) [42]. 

A new Pt(II) polyyne polymer, P15, prepared from the reaction of cfs-[Pt(PPh3)2Cl2] with l,4-diethynyl-2,5-dihexadecyloxybenzene using the extended one pot polymerization route, was tested for its sensing properties and showed fast and reproducible response to relative humidity variations and methanol vapor in surface acoustic-wave (SAW) sensors.46 A SAW sensor was fabricated from polymer P15 as a sensitive membrane, and the polymer was deposited as thin film on the surface of SAW delay lines implemented on three different piezoelectric substrates. High sensitivity and reproducibility were recorded for such devices. The acoustic characterization of the polymer film was also studied with the aid of theoretical results obtained by the perturbation theory. 

Hattori, X, Takahashi, Y, lijima, M., Fukada, E., 1996. Piezoelectric and ferroelectric properties of polyurea-5 thin films prepared by vapor deposition polymerization. J. Appl. Phys. 79,1713-1721. 

He, X. Yao, K, (2006), Crystallization mechanism and piezoelectric properties of solution-derived ferroelectric poly(vinylidene fluoride) thin films. Applied Physics letter. Vol. 89, No. 11, pp. 112909-1 -112902-3, ISSN 0003-6951. 

---