Chenghao Wang

• Peking University

In this study, Pb(Zr0.54Ti0.46)O3 films were prepared by the sol-gel method with Sm doping concentrations of 0, 0.5, 1, 1.5, 2, and 3 mol. %. Their surface morphology, density, crystal structure, piezoelectric, dielectric, and ferroelectric properties were characterized. The results indicated that, unlike Sm-doped lead zirconate titanate (PZT) cera...

In this paper, a novel dual-mass MEMS piezoelectric vector hydrophone is proposed to eliminate the transverse effect and solve the problem of directivity offset in traditional single-mass MEMS piezoelectric vector hydrophones. The reason for the directional offset of the traditional single-mass cantilever MEMS piezoelectric vector hydrophone is exp...

In this study, ZnO thick films suitable for high frequency focused ultrasonic transducers with high piezoelectric properties, and low tensile stress were prepared by DC magnetron sputtering. The ZnO films were analyzed in detail by X-ray diffraction and scanning electron microscope. The sputtering growth process of ZnO films was optimized by improv...

In view of the low sensitivity of MEMS directional sound sensor, a bionic sensitive structure has been studied using finite element method (FEM). The MEMS piezoelectric bionic directional sound sensor, based on ZnO material was prepared and evaluated. In comparison to general structural optimization, which was only capable of determining the maximu...

We proposed a PZT-film-based piezoelectric micromachined ultrasonic transducer (pMUT) with an I-shaped composite diaphragm to improve the sensitivity and resonant frequency of pMUTs with the same diaphragm area. The finite element method (FEM) simulation results indicated that the pMUT with an I-shaped composite diaphragm had relatively high sensit...

This paper focuses on a MEMS piezoelectric vector hydrophone with U-groove. The influence of U-groove on the directivity of the hydrophone is analyzed. The triaxial sensitivity and directivity of different structures are simulated and analyzed by finite element method (FEM). The vector hydrophone chip is prepared by micromechanical process, then en...

Vanadium doped (2.5 at%) ZnO piezoelectric thin films were synthesized on Pt/Ti/SiO2/Si by sol-gel technology. The effects of annealing process on the structure and piezoelectric properties of films were studied. The crystal structure and micro morphology were analyzed by X-ray diffractometer (XRD) and scanning electron microscope (SEM) respectivel...

Targets in layered media can be detected and located using a time reversal (TR)-reversed-time migration (RTM) mixed method. In this study, this single emission-multiple receiving method is tested experimentally by using two types of layered media and three types of targets. The signal reflected at the interface and the signal scattered by the targe...

A modified reverse time migration (RTM) method for dispersed flexural waves is proposed to detect and image the crack in a thin plate. The key point of this method is to take the time reversal (TR) of the expanded flexural wave at a receiver as the backward wave in the cross-correlation imaging condition of RTM, thus the expanded backward wave will...

A square piezoelectric composite diaphragm was analyzed by the finite element method to enhance the sensitivity of a piezoelectric micromachined ultrasound transducer (pMUT). The structures of electrode and piezoelectric film were optimized and a centric electrode was designed to avoid the counteraction of stress in the centre and edges. In order t...

Residual stress is an important factor affecting the sensitivity of piezoelectric micromachined microphone. A symmetric composite vibrating diaphragm was adopted in the micro electro mechanical systems piezoelectric microphone to decrease the residual stress and improve the sensitivity of microphone in this paper. The ZnO film was selected as piezo...

A high-overtone bulk acoustic resonator (HBAR) consisting of a piezoelectric film with two electrodes on a substrate exhibits a high quality factor (Q) and multi-mode resonance spectrum. By analyzing the influences of each layer’s material and structure (thickness) parameters on the effective electromechanical coupling coefficient (Keff2), the reso...

A structure of micro-electro-mechanical system (MEMS) linear phased array based on "multi-cell" element is designed to increase radiation sound pressure of transducer working in bending vibration mode at high frequency. In order to more accurately predict the resonant frequency of an element, the theoretical analysis of the dynamic equation of a fi...

Micro-pattern of 8.2-μm-thick PZT films was prepared on Pt/Ti/SiO2/Si (1 0 0) substrate wafer by combining composite sol–gel and a novel lift-off using ZnO as a sacrificial layer. The processes include ZnO sacrificial layer deposition and patterning, PZT film preparation, and final lift-off. The results reveal the micro-pattern was better than that...

In this paper, the influence of the electrodes on effective electromechanical coupling coefficient k2eff distribution of high-overtone bulk acoustic resonators (HBAR) is investigated using the four-layer thickness extension mode composite resonator model. The k2eff distributions and the spacing of the parallel resonance frequency (SPRF) distributio...

The effect of the annealing process on properties of Pb(Zr0.48Ti0.52)O3 (PZT) thin films prepared by sol-gel method was systematically studied. PZT film deposited by the single layer pre-crystallization processing followed by multilayer crystallization processing is easy to grow along (110) orientation. The PZT films were prepared by the single lay...

The design, fabrication and measuring of piezoelectric micromachined ultrasonic transducers (pMUTs), including the deposition and patterning of PZT films, was investigated. The (100) preferential orientation of PZT film have been deposited on Pt/Ti/SiO2/Si (100) substrates by modified sol–gel method. PZT film and Pt/Ti electrode were patterned by n...

A novel piezoelectric micromachined ultrasonic transducer (pMUT), has been designed, and successfully fabricated .A bridge type structure in flexure mode was adopted for the design of the pMUT element. The transducers comprise a 4-6 mum thick silicon layer, a 1 mum thick thermal oxide layer, and 1.1 mum thick piezoelectric PZT layer . The PZT films...