Ab-initio Modeling of Wurtzite AlBScN and Characterization of AlBScN Piezoelectric thin Film Surface Acoustic Wave Devices Covering 4-8 GHz
I. P. Koutsaroff1 ,* , C. Moe1, Dae Ho Kim1, K. Cheema1, X. Tong2, E. Klein2, P. Yousefian2, and R. H. Olsson III2
1 Akoustis Technologies, Inc., 9805-A Northcross Center Ct., Huntersville, NC 28078 USA
2 Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA 19104 USA
*Corresponding Author: ikoutsaroff@akoustis.com
In the present study, we adopt a comprehensive approach of ab-initio simulations by using a commercial software package VASP 6.5.1 based on Density Functional Theory (DFT) using a projector augmented wave (PAW) method with generalized gradient approximation (GGA) along with Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional and calculations are performed on a grid of points in real space, which allowed us to calculate the full set of piezoelectric and mechanical (acoustic) properties of Al1−xScxN (0≤x≤0.5, AlScN) and Al1-x-yByScxN (AlBScN) at 0K and 300K [1, 2]. To validate the theoretical results, we also conducted sputter deposition and characterization AlBScN layers optimized for growth onto sapphire and SiC substrates [3]. Sezawa mode surface acoustic resonator device devices were fabricated on these substrates and subsequently characterized. The measured phase velocities and piezoelectric coupling coefficients, kt2, allow for a comparison of the measured and ab-initio simulated piezoelectric and stiffness tensors.
References
[1] O. Ambacher, et al., Wurtzite ScAlN, InAlN, and GaAlN crystals, a comparison of structural, elastic, dielectric, and piezoelectric properties, J. Appl. Phys. 28 July 2021; 130 (4): 045102 https://doi.org/10.1063/5.0048647.
[2] I.P., Koutsaroff, et al., High Accuracy Elastic and Piezoelectric Properties Predictions of Al1−xScxN Materials and their Experimental Validation from Microacoustic Resonators within 2.7-5.1 GHz range, Joint ISAF-ICE-EMF-IWPM-PFM Meeting (ISAF 2019) July 14-19, 2019, Lausanne, Switzerland (invited talk).
[3] X. Tong., et al., High-Frequency Sezawa Mode Surface Acoustic Wave resonators Using Boron-doped AlScN on SiC and Sapphire Substrates, (in review, 2025).
Senior Development Engineer
Dr. Ivoyl Koutsaroff is a seasoned expert in microacoustic devices, ferroelectric materials, and advanced piezoelectric technologies, with over 25 years of experience spanning leading-edge roles in North America, Japan, and the U.S. He currently serves as Senior Development Engineer at Akoustis Technologies Inc., a wholly owned subsidiary of SpaceX. His career includes pivotal contributions to RF front-end innovations, MEMS microphone development, and high-performance materials R&D across industry giants such as Qualcomm, Knowles, and Murata.
