Epitaxial AlN on c -plane sapphire by plasma nitriding

Nitridation of sapphire to form epitaxial AlN by microwave plasma containing nitrogen gas has been investigated to be an efficient process. Structural characterization with chemical analysis by X-ray diffraction and X-ray photoelectron spectroscopy shows that an epitaxial AlN film containing oxygen can form on sapphire by using pure nitrogen plasma. Furthermore, nitridation with N 2 /H 2 plasma not only improves the crystallinity of the epitaxial AlN film without oxygen, but also significantly increases the nitridation rate to 9 nm min −1 , resulting in 270 nm thick AlN for 30 min plasma nitriding.