Ultrathin chromium oxide films on the W(100) surface
Donghui Guo1, Qinlin Guo, M S Altman
1State Key Laboratory for Surface Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China.
The Journal of Physical Chemistry. B
|July 21, 2006
Summary
This study explored ultrathin chromium oxide films on W(100) surfaces. Results indicate chromium dioxide (CrO2) forms at low coverage, while chromium trioxide (Cr2O3) forms at higher coverage or increased temperatures.
Area of Science:
- Surface Science
- Materials Science
- Thin Film Technology
Background:
- Understanding the formation of chromium oxide films is crucial for applications in catalysis and electronics.
- Investigating the influence of deposition parameters on film stoichiometry and structure is essential.
Purpose of the Study:
- To investigate the formation and composition of ultrathin chromium oxide films on a W(100) surface.
- To determine the effect of chromium coverage and temperature on the resulting oxide phases.
Main Methods:
- In situ characterization using X-ray photoelectron spectroscopy (XPS).
- In situ characterization using ultraviolet photoelectron spectroscopy (UPS).
- In situ surface structure analysis using low-energy electron diffraction (LEED).
Main Results:
- Ultrathin chromium oxide films were prepared on W(100) under ultrahigh vacuum.
- Chromium dioxide (CrO2) was formed by oxidizing pre-deposited Cr at 300-320 K and low oxygen pressure (<1 monolayer Cr coverage).
- Chromium trioxide (Cr2O3) was detected at higher temperatures or with Cr coverage above 1 monolayer.
Conclusions:
- The stoichiometry of chromium oxide films on W(100) is highly dependent on deposition conditions.
- Controlled oxidation of chromium can yield specific chromium oxide phases (CrO2 or Cr2O3) by tuning coverage and temperature.
- This research provides insights into the controlled synthesis of ultrathin transition metal oxide films.
