This work was supported by the Knut and Alice Wallenberg (KAW) Foundation through a Wallenberg Academy Fellowship (W.W.), the KAW project no.~2022.0090, and the Wallenberg Center for Quantum Technology (WACQT, A.C.), and the Swedish Research Council (VR project No. 2019-04946). H.P.~acknowledges funding by the European Union under the project MSCA-PF-2022-OCOMM. MOVPE of AlN on Si was performed at Otto-von-Guericke-University Magdeburg. The mechanical resonators were fabricated in the Myfab Nanofabrication Laboratory at Chalmers and analyzed in Chalmers Materials Analysis Laboratory. 

Data used for figures in "Thickness dependence of the mechanical properties of piezoelectric high-Q_m nanomechanical resonators made from aluminium nitride" Anastasiia Ciers et.al Materials for Quantum Technology 4, 046301 (2024); arXiv:2410.03944 [cond-mat.mes-hall] (2024)