CeO{sub 2} epitaxial dielectric film on Si substrate by laser ablation technique

Thin films of cerium oxide (CeO{sub 2}) were epitaxially grown on silicon(111) substrates by laser ablation under ultra-high vacuum (UHV) conditions. The laser used as an ArF excimer type (193nm), irradiating a pressed and sintered CeO{sub 2} target (99.9%). Deposition occurred at a UHV condition of {approximately}10{sup {minus}8} torr with substrate temperatures between 500 and 800 C. During growth, both the Si substrate and the CeO{sub 2} target were rotated. The deposition rate was in the range of .2 to 5 nm per minute. Investigation by in situ reflection high-energy electron diffraction (RHEED), ex situ transmission electron microscopy (TEM), and x-ray diffraction revealed that single crystal films can be achieved under certain growth conditions on Si(111). Analysis of high resolution cross-sectional TEM data shows that CeO{sub 2}(111) grows epitaxially on Si(111), but an amorphous layer forms at the interface. This is due to a reaction that occurs between the CeO{sub 2} and the Si substrate during growth. The amorphous region has an undesirable effect on the electrical properties of the CeO{sub 2} films as seen by capacitance-voltage measurements. However, by post annealing the films in oxygen, the interface structure can be controlled and the C-V characteristics of the film aremore » improved.« less