The impact of argon admixture on the c-axis oriented growth of direct current magnetron sputtered Sc_xAl_(1-x)N thin films

摘要

The piezoelectric properties of wurtzite aluminium nitride (w-AlN) are enhanced by alloying with scandium (Sc), thus offering superior properties for applications in micro electro-mechanical systems devices. Sc_xAl_(1-x)N thin films have been prepared by DC reactive magnetron sputtering on Si (100) substrates from a single target. When targeting a concentration range from x = 0 up to x = 0.15, the preparation conditions have been optimized by varying the Ar/N_2 ratio in the sputtering gas. To incorporate an increasing Sc concentration, a higher Ar/N_2 ratio has to be applied during the deposition process. Hence, the argon concentration in the sputtering gas becomes a crucial parameter for microstructure-related parameters. To determine phase purity, degree of c-axis orientation, lattice parameter, and grain size, the Sc_xAl_(1-x)N thin films were investigated by techniques, such as scanning electron microscopy, transmission electron microscopy, and X-ray diffraction.