title: Low-temperature atomic layer epitaxy of AlN ultrathin films by layer-by-layer, in-situ atomic layer annealing.
abstract: Low-temperature epitaxial growth of AlN ultrathin films was realized by atomic layer deposition (ALD) together with the layer-by-layer, in-situ atomic layer annealing (ALA), instead of a high growth temperature which is needed in conventional epitaxial growth techniques. By applying the ALA with the Ar plasma treatment in each ALD cycle, the AlN thin film was converted dramatically from the amorphous phase to a single-crystalline epitaxial layer, at a low deposition temperature of 300 °C. The energy transferred from plasma not only provides the crystallization energy but also enhances the migration of adatoms and the removal of ligands, which significantly improve the crystallinity of the epitaxial layer. The X-ray diffraction reveals that the full width at half-maximum of the AlN (0002) rocking curve is only 144 arcsec in the AlN ultrathin epilayer with a thickness of only a few tens of nm. The high-resolution transmission electron microscopy also indicates the high-quality single-crystal hexagonal phase of the AlN epitaxial layer on the sapphire substrate. The result opens a window for further extension of the ALD applications from amorphous thin films to the high-quality low-temperature atomic layer epitaxy, which can be exploited in a variety of fields and applications in the near future.
authors.affiliation: Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan, R.O.C.
authors.forename: Huan-Yu
authors.initials: HY
authors.lastname: Shih
authors.affiliation: Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan, R.O.C.
authors.forename: Wei-Hao
authors.initials: WH
authors.lastname: Lee
authors.affiliation: Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan, R.O.C.
authors.forename: Wei-Chung
authors.initials: WC
authors.lastname: Kao
authors.affiliation: Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan, R.O.C.
authors.forename: Yung-Chuan
authors.initials: YC
authors.lastname: Chuang
authors.affiliation: Department of Electronic Engineering, Chang Gung University, Tao-Yuan 333, Taiwan, R.O.C.|Department of Radiation Oncology, Chang Gung Memorial Hospital, Tao-Yuan 333, Taiwan, R.O.C.
authors.forename: Ray-Ming
authors.initials: RM
authors.lastname: Lin
authors.affiliation: Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan, R.O.C.
authors.forename: Hsin-Chih
authors.initials: HC
authors.lastname: Lin
authors.affiliation: Kyoto Institute of Technology, Kyoto, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Shiojiri
authors.affiliation: Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan, R.O.C.
authors.forename: Miin-Jang
authors.initials: MJ
authors.lastname: Chen