Crystallinity and Surface Morphology of Reactively Magnetron Sputtered Aluminum Scandium Nitride
Rachel L Adams
Aluminum nitride (AlN) is a low-loss piezoelectric that is commonly used in surface acoustic wave (SAW) and bulk acoustic wave (BAW) based filters for RF communication applications. It has previously been demonstrated that alloying AlN with scandium nitride (ScN) results in an increase of the piezoelectric coefficient up to five times greater than that of pure AlN without significantly increasing losses. This result could have significant impact on next-generation RF-filters. In order for this material to be incorporated into devices, a more thorough understanding of its growth, structural, electrical, and piezoelectric properties is needed. In this work, we investigate the role of deposition parameters during controllable-unbalanced reactive magnetron sputtering on the crystallinity, surface morphology, and composition of aluminum scandium nitride (AlxSc1-xN) on (0001)-oriented sapphire substrates. The conditions considered in this study include the sputter power, the nitrogen gas fraction, the gas ion flux to metal neutral flux ratio (ii/iMe) controlled by the coil current on an external electro-magnet, the substrate temperature, and the sputtering target Al-to-Sc ratio. X-ray photoelectron spectroscopy was used to determine the Al, Sc, and N concentrations in the films. X-ray diffraction of the films showed that the crystallinity was dependent upon ii/iMe and substrate temperature. The surface morphology, determined using atomic force microscopy, showed a similar dependence.
Primary Advisor's Department
Stander Symposium project
"Crystallinity and Surface Morphology of Reactively Magnetron Sputtered Aluminum Scandium Nitride" (2018). Stander Symposium Projects. 1377.