Growth of ultra-thin amorphous Al2O3 films on CoAl(1 0 0)

✍ Scribed by V Rose; V Podgursky; I Costina; R Franchy

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 274 KB
• Volume: 541
• Category: Article
• ISSN: 0039-6028
• DOI: 10.1016/s0039-6028(03)00891-4

✦ Synopsis

The oxidation of a CoAl(1 0 0) surface at 300 K was studied by means of Auger electron spectroscopy, high resolution electron energy loss spectroscopy (EELS), low energy electron diffraction and scanning tunneling microscopy (STM). For an exposure 6 0.3 L, the oxygen atoms are chemisorbed on the CoAl(1 0 0) surface, while for a larger O 2 exposure the oxidation of the surface sets in. For an exposure P 300 L the surface is entirely covered with amorphous Al 2 O 3 (a-Al 2 O 3 ) whereas the Co atoms seem to be unaffected. The EEL spectra of a-Al 2 O 3 exhibit Fuchs-Kliewer modes at around 640 and 890 cm À1 . The thickness of the a-Al 2 O 3 film is estimated to be 7.1 ± 0.7 A A. The STM images show that the oxide grows as large islands which cover the whole surface. The band gap of the ultra-thin a-Al 2 O 3 film on CoAl(1 0 0) is found to be 3.2 eV and thus it is strongly diminished with respect to the bulk value.