Atomic layer deposition and characterization of scandium aluminum nitride

We report the growth of scandium aluminum nitride (ScAlN) thin films utilizing plasma-enhanced atomic layer deposition (PE-ALD). The scandium (Sc) content is controllably varied up to 25% by tuning the deposition parameters. These films exhibited excellent surface morphology with a small root mean square roughness of 0.5 nm or less. The ALD growth window for ScAlN is identified between 225 and 250 °C, with a precursor pulse saturation achieved at 1.5 s. The piezoelectric coefficients (d33) were characterized using piezoresponse force microscopy (PFM) and laser-Doppler vibrometry (LDV) measurements and found to increase from 9.3 pm/V for 10% Sc to 17 pm/V for 25% Sc, which are comparable to those reported for ScAlN grown by conventional sputtering or epitaxial methods.