Influence of defects in low-energy nitrogen ion beam assisted gallium nitride thin film deposition

摘要

Epitaxial GaN thin films were grown by low-energy nitrogen ion beam assisted deposition of gallium on c-plane sapphire. By applying X-ray diffraction and transmission electron microscopy, the influence of the ion irradiation induced defects on the formation of the undesired cubic GaN polytype in the hexagonal films is investigated. The results show that in all films containing the cubic polytype it appears in twinned form. An increase of the ion energy as well as the ratio of nitrogen ion flux and gallium atom flux (I/A -ratio) leads to an increase in the amount of cubic polytype in the films. The observations are discussed considering the ion beam induced defect creation.