Piezoelectric Aluminum Nitride Films PDF Download
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Author: Michael T. Duffy
Publisher:
ISBN:
Category :
Languages : en
Pages : 139
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Piezoelectric films of AlN and GaN were grown on sapphire substrates for use in the generation, propagation, and processing of surface acoustic waves. The films were grown by CVD heteroepitaxy using the metal-organic reactants trimethyl aluminum or trimethyl gallium. Greatest emphasis was placed on optimization of the aluminum nitride-sapphire system as determined by the (1,1,-2,0)AlN/(1,-1,0,2)Al2O3 epitaxial relationship. The films were examined with respect to crystallography, surface topography, optical properties, uniformity, and ease of polishing. A wide range of epitaxial growth temperatures was covered in order to establish optimum conditions for the growth of relatively thick films with minimum surface structure and residual composite strain. The possibility of growing silicon on the same substrate with AlN in a side-by-side configuration was examined and shown to be feasible. Aluminum transducer patterns were fabricated on some samples to form delay lines.
Author: Michael T. Duffy
Publisher:
ISBN:
Category :
Languages : en
Pages : 139
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Book Description
Piezoelectric films of AlN and GaN were grown on sapphire substrates for use in the generation, propagation, and processing of surface acoustic waves. The films were grown by CVD heteroepitaxy using the metal-organic reactants trimethyl aluminum or trimethyl gallium. Greatest emphasis was placed on optimization of the aluminum nitride-sapphire system as determined by the (1,1,-2,0)AlN/(1,-1,0,2)Al2O3 epitaxial relationship. The films were examined with respect to crystallography, surface topography, optical properties, uniformity, and ease of polishing. A wide range of epitaxial growth temperatures was covered in order to establish optimum conditions for the growth of relatively thick films with minimum surface structure and residual composite strain. The possibility of growing silicon on the same substrate with AlN in a side-by-side configuration was examined and shown to be feasible. Aluminum transducer patterns were fabricated on some samples to form delay lines.
Author: Gustavo Sanchez Mathon
Publisher:
ISBN:
Category :
Languages : en
Pages : 432
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Book Description
Polycrystalline aluminum nitride thin films were produced with a microwave-plasma enhanced chemical vapor deposition technique. The plasma-injector distance, the substrate temperature and the RF bias were the main variables which allowed achieving this objective. At the time, it was possible to control the preferential orientation as 0001 or 1010, both interesting for piezoelectric applications. The growth mechanisms that conducted to film microstructure development under different process conditions were explained, enriched by the comparison with a physical vapor deposition sputtering technique. The obtained films were characterized in their piezoelectric performance, including the construction of surface acoustic wave devices and bulk acoustic wave devices. Adequate piezoelectric response and acoustic velocities were obtained for 0001 oriented films, while 1010 oriented films did not show piezoelectric response under the configurations essayed. An extensive analysis was done in order to explain these behaviors.
Author: John Preston Harman
Publisher:
ISBN:
Category : Aluminum nitride
Languages : en
Pages :
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Author:
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ISBN:
Category :
Languages : en
Pages :
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A Rapid Thermal Annealing (RTA) system was used to anneal sputtered and MOVPE grown Aluminum Nitride (AlN) thin films at temperatures up to 1000°C in ambient and controlled environments. According to Energy Dispersive X-Ray Analysis (EDAX), the films annealed in an ambient environment rapidly oxidize after five minutes at 1000°C. Below 1000°C the films oxidized linearly as a function of annealing temperature which is consistent with what has been reported in literature [1]. Laser Doppler Vibrometry (LDV) was used to measure the piezoelectric coefficient, d33, of these films. Films annealed in an ambient environment had a weak piezoelectric response indicating that oxidation on the surface of the film reduces the value of d33. A high temperature furnace has been built that is capable of taking in-situ measurements of the piezoelectric response of AlN films. In-situ d33 measurements are recorded up to 300°C for both sputtered and MOVPE-grown AlN thin films. The measured piezoelectric response appears to increase with temperature up to 300°C possibly due to stress in the film.
Author: Charlee Fansler
Publisher:
ISBN: 9783836469722
Category : Technology & Engineering
Languages : en
Pages : 124
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Book Description
Aluminum Nitride (AlN) thin films can be used for many device applications; for example, Surface Acoustic Wave (SAW) devices, microelectromechanical systems (MEMS) applications, and packaging applications. In this work, AlN is the critical layer in the fabrication process. One challenge is reliable deposition over wafer size substrates. The method of interest for deposition is pulsed DC sputtering. The (002) plane is the desired plane for its piezoelectric properties. The surface roughness of the deposited AlN is low and adheres well to the substrate. An AlN layer was deposited on a UNCD/Si substrate. Al was deposited on the AlN layer to form the IDTs (interdigital transducers) for SAW devices. SAW devices were fabricated on quartz - ST substrate. To verify the SAW devices work, they were tested using a network analyzer. This book discusses these results and parameters for AlN film deposition, film properties and implications for devices. This book would be beneficial for professionals, scientists, engineers, and graduate students in science and engineering working in the areas of wide bandgap semi-conductors, nitrides and piezoelectric materials and various acoustic wave devices.
Author: Adam Kabulski
Publisher:
ISBN:
Category : Aluminum nitride
Languages : en
Pages :
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Author: Seth E. Boeshore
Publisher: ProQuest
ISBN: 9780542856082
Category :
Languages : en
Pages : 332
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Piezoelectric unimorph cantilever beams have been fabricated from the deposited films and used for the first demonstration of piezoelectric transduction on titanium. At large displacements, these beams exhibit nonlinear spring softening. An analytical model has been developed to accurately describe the frequency response of these beams and to calculate the material properties of the film. Test results from these beams show that d 31 and k231 for the films are within 10% of the reported values.
Author: Masood Hasheminiasari
Publisher:
ISBN:
Category : Aluminum nitride
Languages : en
Pages : 168
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Author: Md Sajeeb Rayhan
Publisher:
ISBN:
Category : Microelectromechanical systems
Languages : en
Pages : 145
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Microelectromechanical systems (MEMS) sensors using ultrathin aluminum nitride (AlN) film were developed and fabricated using conventional photolithography techniques in the class 100 clean room with a view to integrate them in flexible substrates along with flexible electronics. The MEMS sensors were designed, analytically modeled, fabricated and characterized. Some of the MEMS sensors were only designed and simulated using finite element method (FEM) for the scope of the dissertation. These MEMS sensors can be applied to many applications such as automobile, robotics, biomedical, biometrics, health condition monitoring, GPS tracking devices, smartphones and aircrafts. MEMS pressure sensors using AlN based piezoelectric film were designed, fabricated and characterized in the form of array of cantilever based structures. A 300 nm thick ultrathin and flexible AlN film with a feature size of ~12 [micron] which was deposited using DC reactive magnetron sputtering system and sandwiched between two electrodes to induce cantilever shaped structures acted as the sensing element of the cantilever sensors. After fabrication, several cantilevers were chosen for electrical characterization. The pressure sensors were characterized in a probe station system to measure the piezoelectric voltage signals and power spectral densities. With the help of simulation results, numerical modeling was also carried out to find the theoretical output voltage ranges and sensitivity of the cantilevers. The simple and flexible cantilevers form the basis for future piezoelectric energy harvesters, pressure sensors, fingerprint sensors and accelerometers using ultrathin AlN film those can be integrated on a system-on-chip (SoC) circuit. Initially, the ultrathin AlN films were developed by changing the deposition temperature and Ar/N2 gas flow ratio and characterized using SEM, XRD and EDX to analyze the quality of the film. Stress analyses were taken into consideration to check the mechanical strength and reliability of the pressure sensors. In addition, bending performance was also analyzed by calculating the radius of curvature (ROC) of the cantilevers. Finally, noise performance was also analyzed. Ultra-thin AlN based novel flexible MEMS fingerprint sensors were designed using finite element method i.e., CoventorWare® with a view to improve the pixel resolution and, hence, the quality of scanned fingerprint image. Two different sized pixel dimensions were used for the design of three fingerprint sensors; they are: a) FPS725A b) FPS725B, and c) FPS1016. The pixel dimension for FPS725A and FPS725B was 35 [micron] by 35 [micron]. The pixel feature was equivalent to an imaging resolution of 725 dot-perinch (dpi). The other sensor had a pixel size of 25 [micron] by 25 [micron] and was equivalent to an imaging resolution of 1016 dpi. In both type of sensors, 200 nm thick, ultrathin AlN film was used as the sensing element. The difference between FPS725A and FPS725B was the location of the sensing element. In FPS725A, AlN film was deposited on top of Al2O3 diaphragm while in FPS725B, AlN was located inside the diaphragm. The fabrications process flow will be discussed in details in the fingerprint sensor chapter. In brief, the fingerprint sensors were comprised of array of pixels and each pixel was made of a cavity like structure which was basically an aluminum oxide (Al2O3) based structure. Underneath the cavity like structure, there was an adjacent piezoelectric plate or film which was sandwiched between two metal electrodes. The total area of the sensors is identical and considered to be 15 mm by 15 mm for practical use. Piezoelectric output voltage with respect to various applied finger pressure were calculated using the stress contour found from the simulation results. Finally, piezoelectric response for each sensor for different finger pressure was found from the slope of the piezoelectric voltage versus applied force plot. The average piezoelectric responses are found to be 225.74 V/N, 115.58 V/N, and 125.52 V/N for FPS725A, FPS725B, and FPS1016, respectively. Stress analysis and noise performance of the sensors were studied. For practical use, the CMOS readouts will be taken from the Silicon substrate through the electrical metallization of pure metal electrodes which will be covered in the chapter. An AlN based piezoelectric z-axis MEMS accelerometer was designed and simulated using CoventorWare®. Modal harmonic analysis was carried out and the simulated resonant frequency was found to be 2.26 kHz. Various loads were applied on top proof mass of the accelerometer ranging from 1g to 10g. Piezoelectric output voltages due to applied loads were calculated. The voltages ranged from 0.00082 V to 0.000082 V. The piezoelectric response or sensitivity was also calculated and found to be 0.000082 V/N. Noise performances was also analyzed and noise equivalent acceleration (NEA) was calculated. Noise equivalent acceleration was found to be 0.253 g/[square root]Hz.
Author:
Publisher:
ISBN:
Category : Microelectromechanical systems
Languages : en
Pages :
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