**4. Conclusions**

In this paper, we demonstrate a method to grow AlScN films with a high degree of *c*-axis orientation using same process parameters on various types of substrates, e.g., SiO2, (100) Si and poly-Si. This approach is to introduce a 20 nm thin AlN seed layer, which itself grows with good textural properties on most smooth substrates. By using an AlN seed layer, the wurtzite-type structure is established in the AlScN layer, resulting in a good *c*-axis orientation. The lattice mismatch between AlN and AlScN films seems to be of secondary importance in this context. In addition, there is only a small reduction (4.5%) from 9.33 pm/V to 8.91 pm/V in the piezoelectric coefficient d33,*<sup>f</sup>* of AlScN layers in the presence of a 20 nm AlN seed layer with lower dielectric permittivity and piezoelectric coefficient.

**Author Contributions:** Conceptualization, J.S., S.F., B.W., and F.L.; methodology, J.S., S.F., D.K., and F.N.; software, J.S. and N.W.; validation, J.S.; formal analysis, J.S. and N.W.; investigation, J.S., M.Z.G., N.W., M.R.I., and A.L.; resources, D.K., L.K., B.W., and F.L.; data curation, J.S. and N.W.; writing original draft preparation, J.S.; writing review and editing, J.S., S.F., N.W., F.N., L.K., and F.L.; visualization, J.S.; supervision, S.F., D.K., and F.L.; project administration, J.S., S.F., and F.L.; funding acquisition, F.L., B.W. and L.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was funded by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) under the scheme of the collaborative research center (CRC) 1261 'Magnetoelectric Sensors: From Composite Materials to Biomagnetic Diagnostics' and the project "ForMikro-SALSA" (grant no. 16ES1053) from the Federal Ministry of Education and Research (BMBF).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available on reasonable request from the corresponding author.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.
