Growth of epitaxial Pr2O3 layers on Si(111)

The growth of PrO3 layers on Si(111) has been studied by X-ray diffraction, Low-energy electron diffraction (LEED) and atomic force microscopy (AFM). Pr2O3 starts to grow as a 0.6-nm thick layer corresponding to one unit cell of the hexagonal phase (1 ML). The X-ray results indicate that layers thicker than 0.6 nm do not grow with the hexagonal phase. Growth takes place at a sample temperature of 500-550 degrees C. Annealing of the monolayer in UHV at a temperature above 700 degrees C leads to the formation of Pr2O3 and PrSi2 islands. Silicide islands are found only at annealing in UHV and do not occur at annealing in oxygen atmosphere of 10(-8) mbar. The LEED pattern after heating to 730 degrees C shows a (2 x 2) and (root 3 x root 3) superstructure and after heating to 1000 degrees C a (1 x 5) superstructure occurs. The superstructures seen in the LEED pattern arise from silicide structures in the area between the islands. The silicide remains on the surface and cannot be removed with flashing to 1100 degrees C. Further deposition of Pr2O3 on the surface covered with silicide phases does not lead to growth of ordered layers. (c) 2006 Elsevier Ltd. All rights reserved.