Comparison of AIN Films Grown by RF at Magnetron Sputtering and Ion-Assisted Molecular Beam Epitaxy

Crystalline aluminum nitride (AlN) thin films were formed on various substrates by using RF magnetron sputtering of an A1 target in a nitrogen plasma and also by ion-assisted molecular beam epitaxy (IAMBE). Basal-oriented AlN/(111) Si showed a degradation of crystallinity with increased substrate temperature from 550 to 770 °C, while the crystallinity of AlN/(0001) Al₂O₃ samples improved from 700 to 850 °C. The optical absorption characteristics of the AlN/(0001) Al₂O₃ films as grown by both deposition methods revealed a decrease in sub-band gap absorption with increased substrate temperature.