Control of temperature coefficient of frequency in zinc oxide thin film bulk acoustic wave resonators at various frequency ranges

Yoshino, Yukio; Takeuchi, Masaki; Inoue, K.; Makino, Takahiro; Arai, Seiichi; Hata, Toshiyuki

doi:10.1016/s0042-207x(02)00117-3

Cited by 19 publications

(6 citation statements)

References 5 publications

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“…Due to their singular properties, ZnO thin films have been extensively studied in the last years. Among other main applications we have; optical devices [1], piezoelectric sensors [2], superficial acoustic waves [3], gas sensors [4], and transparent electrodes [5,6], among others.…”

Section: Introductionmentioning

confidence: 99%

Ga-doped ZnO thin films: Effect of deposition temperature, dopant concentration, and vacuum-thermal treatment on the electrical, optical, structural and morphological properties

Gómez

Olvera

2006

Materials Science and Engineering: B

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Section: Introductionmentioning

confidence: 99%

Ga-doped ZnO thin films: Effect of deposition temperature, dopant concentration, and vacuum-thermal treatment on the electrical, optical, structural and morphological properties

Gómez

Olvera

2006

Materials Science and Engineering: B

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“…Zinc oxide is a good candidate for evaluating the Tauc method because it has been widely studied for a number of useful applications [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Among these applications, the band-gap plays a central and fundamental role as it controls many absorption and conductivity phenomena.…”

mentioning

confidence: 99%

“…This has allowed a statistical evaluation of the Tauc method as well as giving us the ability to calculate the NEAR values for all of these samples. 4 It is recognized that our analysis brings together an extremely large number of measurements of (ideally) the same composition ZnO material in thin film form, though admittedly examining a wide range of different possible microstructures due to their different processing histories. As a first measure of the population under study, we plot the cumulative probability distribution of E g values as reported in the original publication, as shown in Fig.…”

mentioning

confidence: 99%

Evaluation of the Tauc method for optical absorption edge determination: ZnO thin films as a model system

Viezbicke

Patel

Davis

et al. 2015

Phys. Status Solidi B

935

419

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One of the most frequently used methods for characterizing thin films is UV–Vis absorption. The near‐edge region can be fitted to a simple expression in which the intercept gives the band‐gap and the fitting exponent identifies the electronic transition as direct or indirect (see Tauc et al., Phys. Status Solidi 15, 627 (1966); these are often called “Tauc” plots). While the technique is powerful and simple, the accuracy of the fitted band‐gap result is seldom stated or known. We tackle this question by refitting a large number of Tauc plots from the literature and look for trends. Nominally pure zinc oxide (ZnO) was chosen as a material with limited intrinsic deviation from stoichiometry and which has been widely studied. Our examination of the band gap values and their distribution leads to a discussion of some experimental factors that can bias the data and lead to either smaller or larger apparent values than would be expected. Finally, an easily evaluated figure‐of‐merit is defined that may help guide more accurate Tauc fitting. For samples with relatively sharper Tauc plot shapes, the population yields Eg(ZnO) as 3.276 ± 0.033 eV, in good agreement with data for single crystalline material.

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“…Crystalline structures of the films were determined using X‐ray diffraction (XRD; Siemens D5000), and the average grain sizes were calculated using the Debye–Scherrer formula with the removal of the equipment induced beam broadening . The c ‐axis stress values in the ZnO films were estimated using the following equation :

σ_{film} = \frac{2 c_{13}^{2} - c_{33} (c_{11} + c_{12})}{2 c_{13}} \times \frac{c_{film} - c_{bulk}}{c_{bulk}},

where the elastic stiffness constants c 11 , c 12 , c 13 and c 33 of the ZnO are 208.8, 119.7, 104.2, and 213.8 GPa, respectively . The last term ( c film – c bulk )/ c bulk is the strain in the ZnO film along c ‐axis, and c film is the lattice constant of the film obtained from the position of the (0002) diffraction peak, c bulk is the unstrained lattice parameter of the bulk ZnO taken as 0.52069 nm.…”

Section: Methodsmentioning

confidence: 99%

Characterization of the surface acoustic wave devices based on ZnO/nanocrystalline diamond structures

Pang

Garcia‐Gancedo

et al. 2013

Phys. Status Solidi A

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Nanocrystalline ZnO films with strong (0002) texture and fine grains were deposited onto ultra-nanocrystalline diamond (UNCD) layers on silicon using high target utilization sputtering technology. The unique characteristic of this sputtering technique allows room temperature growth of smooth ZnO films with a low roughness and low stress at high growth rates. Surface acoustic wave (SAW) devices were fabricated on ZnO/UNCD structure and exhibited good transmission signals with a low insertion loss and a strong side-lobe suppression for the Rayleigh mode SAW. Based on the optimization of the layered structure of the SAW device, a good performance with a coupling coefficient of 5.2% has been realized, promising for improving the microfluidic efficiency in droplet transportation comparing with that of the ZnO/Si SAW device. An optimized temperature coefficient of frequency of À23.4 ppm 8C À1 was obtained for the SAW devices with the 2.72 mm-thick ZnO and 1.1 mm-thick UNCD film. Significant thermal effect due to the acoustic heating has been redcued which is related to the temperature stability of the ZnO/UNCD SAW device.

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Control of temperature coefficient of frequency in zinc oxide thin film bulk acoustic wave resonators at various frequency ranges

Cited by 19 publications

References 5 publications

Ga-doped ZnO thin films: Effect of deposition temperature, dopant concentration, and vacuum-thermal treatment on the electrical, optical, structural and morphological properties

Ga-doped ZnO thin films: Effect of deposition temperature, dopant concentration, and vacuum-thermal treatment on the electrical, optical, structural and morphological properties

Evaluation of the Tauc method for optical absorption edge determination: ZnO thin films as a model system

Characterization of the surface acoustic wave devices based on ZnO/nanocrystalline diamond structures

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