Aerosol Deposition (AD) and Its Applications for Piezoelectric Devices

Technological innovations in manufacturing processes are critical for devices that require high-quality thick piezoelectric ceramic films. However, ceramic films synthesized by conventional methods usually suffer from mechanical failures, poor adhesion, reliability, and rough interfaces. Furthermore, with traditional piezoelectric thin film methods, such as sputtering, sol-gel, pulsed laser, and etc., it is difficult to synthesize piezoelectric films with complex material compositions and with multiple dopants in a short deposition time and over a large surface area, in general. The aerosol deposition (AD) process is a unique approach for depositing thick piezoelectric ceramic films to overcome these technological hurdles. In this process, (sub)-micron ceramic particles fluidized by gas flow are accelerated in a low-vacuum environment at velocities of up to 100–300 m/s to be impacted on the desired substrates. The impact results in a thick, dense, uniform, and homogeneous polycrystalline ceramic film formed at room temperature without the need for any additional heating to solidify the resulting film. The process is extremely cost-effective and requires comparatively simple equipment installation that is integratable with modern industrial fabrication facilities. This technique is particularly useful for fabricating piezoelectric thick films for microactuators, sensors, and energy-harvesting devices. This chapter describes the mechanisms and features of the AD process, followed by applications of AD for fabricating piezoelectric materials and devices.