Surface Morphology and Microstructure of Pulsed DC Magnetron Sputtered Piezoelectric AlN and AlScN Thin Films

Abstract

Reactive pulsed DC magnetron co‐sputtering is used to grow piezoelectric aluminum nitride (AlN) and aluminum scandium nitride (AlScN) thin films on Si(001) substrates. By using grazing incidence X‐ray diffraction (GIXRD), scanning electron microscopy (SEM), and piezoresponse force microscopy (PFM), we investigate how the microstructure and the presence of misoriented grains affect the piezoelectric properties of the material. N2 concentration and target‐to‐substrate distance are finely tuned to achieve thin films without misoriented grains, resulting in Al0.87Sc0.13N thin films with low roughness, high degree of c‐axis orientation, homogenous polarity, and piezoelectric coefficient d33 = −12.3 pC/N.