Preparation and characterization of ZnO microcantilever for nanoactuation
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NANO EXPRESS
Open Access
Preparation and characterization of ZnO microcantilever for nanoactuation Peihong Wang1, Hejun Du1*, Shengnan Shen1,2, Mingsheng Zhang2 and Bo Liu2
Abstract Zinc oxide [ZnO] thin films are deposited using a radiofrequency magnetron sputtering method under room temperature. Its crystalline quality, surface morphology, and composition purity are characterized by X-ray diffraction [XRD], atomic force microscopy [AFM], field-emission scanning electron microscopy [FE-SEM], and energy-dispersive X-ray spectroscopy [EDS]. XRD pattern of the ZnO thin film shows that it has a high c-axispreferring orientation, which is confirmed by a FE-SEM cross-sectional image of the film. The EDS analysis indicates that only Zn and O elements are contained in the ZnO film. The AFM image shows that the film’s surface is very smooth and dense, and the surface roughness is 5.899 nm. The microcantilever (Au/Ti/ZnO/Au/Ti/SiO2/Si) based on the ZnO thin film is fabricated by micromachining techniques. The dynamic characterizations of the cantilever using a laser Doppler vibrometer show that the amplitude of the cantilever tip is linear with the driving voltage, and the amplitude of this microcantilever’s tip increased from 2.1 to 13.6 nm when the driving voltage increased from 0.05 to 0.3 Vrms. The calculated transverse piezoelectric constant d31 of the ZnO thin film is -3.27 pC/N. This d31 is high compared with other published results. This ZnO thin film will be used in smart slider in hard disk drives to do nanoactuation in the future. Keywords: ZnO thin film, piezoelectric cantilever, micromachining technique, transverse piezoelectric constant
Introduction As the recording density of hard disk drive [HDD] further increases, the spacing between the slider and the disk decreases quickly. A 10-Tb/in2 recording density requires a 2 to 3 nm or even less of head-media spacing when HDD is working [1]. In that case, contact between slider and disk will not be avoided completely. So, it is necessary to detect the slider-disk contact and then adjust the spacing to decrease the damage to the headdisk interface. Due to quick response and contact detection ability, many piezoelectric sensors/actuators based on bulk and thin film lead zirconate titanate [PZT] have been proposed in order to solve the above problem [2,3]. However, it is hard to fabricate a bulk PZT material into a microscale dimension. Meanwhile, the deposition of PZT thin film usually requires processing at over 600°C [4], which is not compatible with fabrication of magnetic heads in HDD technology. Compared to PZT * Correspondence: [email protected] 1 School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Republic of Singapore Full list of author information is available at the end of the article
material, ZnO thin film also has good piezoelectric quality, and its microfabrication does not need head process under very high temperature [5]. So, ZnO film-based piezoelectric sensors/actuators are bei
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