The present Master's Thesis regards the impact of Scandium doping on Aluminum Nitride (AlN) thin films. Two very interesting applications of Sc-doped AlN (ScAlN) are treated in depth, namely the improvement in MEMS piezoelectric resonator performances and the study of its ferroelectric properties. While the first study poses itself as an optimization of something already present, the second one represents a step towards the opening of new research lines. The present work is divided into three main Chapters. The first one is the introduction of the Thesis work, describing the state of the art in the field of MEMS resonators. Moreover, physical descriptions of the phenomena of piezoelectricity and ferroelectricity, the ones on which the studied technologies rely, are given.