Publication Date:
2016-06-23
Description:
On highly oxygen deficient thin films of hafnium oxide (hafnia, HfO 2− x ) contaminated with adsorbates of carbon oxides, the formation of hafnium carbide (HfC x ) at the surface during vacuum annealing at temperatures as low as 600 °C is reported. Using X-ray photoelectron spectroscopy the evolution of the HfC x surface layer related to a transformation from insulating into metallic state is monitored in situ . In contrast, for fully stoichiometric HfO 2 thin films prepared and measured under identical conditions, the formation of HfC x was not detectable suggesting that the enhanced adsorption of carbon oxides on oxygen deficient films provides a carbon source for the carbide formation. This shows that a high concentration of oxygen vacancies in carbon contaminated hafnia lowers considerably the formation energy of hafnium carbide. Thus, the presence of a sufficient amount of residual carbon in resistive random access memory devices might lead to a similar carbide formation within the conducting filaments due to Joule heating.
Print ISSN:
0003-6951
Electronic ISSN:
1077-3118
Topics:
Physics
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