Theoretical investigations of polytypism in AlN thin films

✍ Scribed by Ito, Tomonori ;Ito, Takumi ;Ammi, Daisuke ;Akiyama, Toru ;Nakamura, Kohji

• Book ID: 105365800
• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 331 KB
• Volume: 207
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.200983431

✦ Synopsis

Abstract

The polytypism in AlN is theoretically investigated using ab initio pseudopotential, empirical interatomic potential, and Monte Carlo simulation. In bulk form, 2H‐AlN is stable without polytypes because of its large energy profit to 3C, 6H, and 4H structures. On the Si(001) substrate, the AlN thin films varies their structures from 3C at the film thickness h ≤ 4 monolayers (MLs) to (0001)‐oriented 2H tilted 5° at the h≥ 2345 MLs via (0001)‐oriented 2H with two misfit dislocations. This reveals that the large lattice mismatch system destabilizes the metastable 3C‐AlN(001) to make the stable 2H‐AlN appear with different orientation. The 4H‐AlN can be stably formed on the 4H‐SiC(11‐20) under Al‐rich condition, whereas the 2H‐AlN may appear under N‐rich condition. This results from the distinctive behavior of Al (N) after N (Al) pre‐depositions. These results are consistent with experimental findings for the polytypism in AlN thin films grown on various substrates.