Deposition, Characterization, and Modeling of Scandium-Doped Aluminum Nitride Thin Film for Piezoelectric Devices

Abstract

In this work, we systematically studied the deposition, characterization, and crystal structure modeling of ScAlN thin film. Measurements of the piezoelectric device’s relevant material properties, such as crystal structure, crystallographic orientation, and piezoelectric response, were performed to characterize the Sc0.29Al0.71N thin film grown using pulsed DC magnetron sputtering. Crystal structure modeling of the ScAlN thin film is proposed and validated, and the structure–property relations are discussed. The investigation results indicated that the sputtered thin film using seed layer technique had a good crystalline quality and a clear grain boundary. In addition, the effective piezoelectric coefficient d33 was up to 12.6 pC/N, and there was no wurtzite-to-rocksalt phase transition under high pressure. These good features demonstrated that the sputtered ScAlN is promising for application in high-coupling piezoelectric devices with high-pressure stability.

Self-Rolled-Up Aluminum Nitride-Based 3D Architectures Enabled by Record-High Differential Stress

“…However, in the Al 1– x Sc x N/AlN stack, the lattice parameter (along the a -axis) and the thermal expansion coefficient of the MBE-grown Al 1– x Sc x N increase with increasing Sc composition. ,, Therefore, based on the lattice-mismatch strain, the Al 1– x Sc x N top layer should be under biaxial compression (approx. −11 GPa ( x = 0.3)) relative to AlN, but interestingly, the Al 1– x Sc x N/AlN stack rolls upward and the diameter decreases as the Sc composition is increased . This indicates that the delta stress originating due to E f and α AlN – α AlScN is increasingly positive as we move vertically above the Al 1– x Sc x N/AlN stack and is much greater than the calculated value of +5.9 GPa ( x = 0.3). , Note that our experiments are limited to a Sc composition of x = 0.3, as beyond that, the thermal-expansion mismatch tends to exceed the fracture toughness of the Al 1– x Sc x N film, and the film starts to crack .…”

“…−11 GPa (x = 0.3)) relative to AlN, but interestingly, the Al 1−x Sc x N/AlN stack rolls upward and the diameter decreases as the Sc composition is increased. 59 This indicates that the delta stress originating due to E f and α AlN − α AlScN is increasingly positive as we move vertically above the Al 1−x Sc x N/AlN stack and is much greater than the calculated value of +5.9 GPa (x = 0.3). 52,53 Note that our experiments are limited to a Sc composition of x = 0.3, as beyond that, the thermal-expansion mismatch tends to exceed the fracture toughness of the Al 1−x Sc x N film, and the film starts to crack.…”

Dawn of nitride ferroelectric semiconductors: from materials to devices

“…They investigated the electric field induced inversion domains, as well as the non-switched domains at the bottom electrode interface, providing critical information for understanding the domain evolution process during polarization switching in wurtzite materials. Subsequently, the impact of the nitrogen-to-argon gas ratio and target power ratios, plasma modes, sputter power, deposition temperature, crystal orientation, film stress, surface roughness, Sc content, and deposition rate on ferroelectric properties of ScAlN have been intensively investigated [62,64,[144][145][146][147][148][149][150][151][152][153].…”

Stepped-Tube Backside Cavity Piezoelectric Ultrasound Transducer Based on Sc0.2AI0.8N Thin Films

“…Before the first deposition, the wafer needs to undergo pretreatment at a high temperature of 450 °C for 5 min under vacuum. This process is designed to remove impurities and water vapor adhered to the SOI wafer [ 25 ]. Then, a one-step deposition of Sc 0.096 AI 0.904 N/Mo/Sc 0.2 AI 0.8 N/Mo stacked layers was carried out.…”