title: Anomalous hexagonal superstructure of aluminum oxide layer grown on NiAl(110) surface.
abstract: A modified method for the fabrication of a highly crystallized layer of aluminum oxide on a NiAl(110) surface is reported. The fabrication method involves the multistep selective oxidation of aluminum atoms on a NiAl(110) surface resulting from successive oxygen deposition and annealing. The surface morphology and local electronic structure of the novel aluminum oxide layer were investigated by high-resolution imaging using scanning tunneling microscopy (STM) and current imaging tunneling spectroscopy. In contrast to the standard fabrication method of aluminum oxide on a NiAl(110) surface, the proposed method produces an atomically flat surface exhibiting a hexagonal superstructure. The superstructure exhibits a slightly distorted hexagonal array of close-packed bright protrusions with a periodicity of 4.5 ± 0.2 nm. Atomically resolved STM imaging of the aluminum oxide layer reveals a hexagonal arrangement of dark contrast spots with a periodicity of 0.27 ± 0.02 nm. On the basis of the atomic structure of the fabricated layer, the formation of α-Al2O3(0001) on the NiAl(110) surface is suggested.
authors.affiliation: Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita 565-0871, Japan.
authors.forename: Pawel
authors.initials: P
authors.lastname: Krukowski
authors.forename: Songpol
authors.initials: S
authors.lastname: Chaunchaiyakul
authors.forename: Yuto
authors.initials: Y
authors.lastname: Minagawa
authors.forename: Nami
authors.initials: N
authors.lastname: Yajima
authors.forename: Megumi
authors.initials: M
authors.lastname: Akai-Kasaya
authors.forename: Akira
authors.initials: A
authors.lastname: Saito
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kuwahara