ScxAl1-xN and YxAl1-xN thin films were deposited in a ultra high vacuum system using reactive magnetron co-sputtering from elemental Al  Sc and Y targets in Ar/N2 Their mechanical  electrical  optical  and piezoelectrical properties were investigated with the help of transmission electron microscopy  xray diffraction  ellipsometry  I-V and C-V measurements  and two different techniques for piezoelectric characterization: piezoresponse force microscopy and double beam interferometry