Growth of High-Quality AlN Films through Polarity and Vacancy Defects Control

The development of electronic devices toward miniaturization and integration has put forward higher requirements for the crystal quality of aluminum nitride (AlN). However, the AlN films prepared experimentally often contain defects, which greatly reduces their crystal quality and limits their application in the field of microelectronics and semiconductors. To clarify the mechanism for improving the crystal quality, the AlN film homoepitaxial growth processes on polar substrates with various vacancy concentrations were studied by molecular dynamics. The film deposition on perfect substrate was used as the control group. The results show that the epilayer is composed of alternating layers of hexagonal diamond and cubic diamond in a lamellar structure. The dislocation 1/3 ⟨1–210⟩ within epitaxial layers has a strong longitudinal growth ability, while there is a stronger horizontal growth trend for 1/3 ⟨1–100⟩. The film grown on the Al-polar substrate has a higher density and lower roughness compared to the N-polar substrate. The epitaxial layers prepared on the Al3 substrate and N1 substrate have more abundant hexagonal diamond structure and lower dislocation density, indicating that the internal structure of the film can be controlled by the synergy of polarity and vacancy defect. The lower residual stress of the film prepared on the Al-polar substrate makes it more suitable for precision machining. This study has revealed the influence of substrate polarity and vacancy defect on AlN films quality, providing theoretical guidance for the preparation of high-quality AlN films.