Praseodymium compound formation in silicon by ion beam synthesis

The compound formation in the ternary system Pr-Si-O initiated by ion beam synthesis inside bulk-Si was studied by transmission electron microscopy and X-ray diffraction. The oxygen content was varied by additional O+ ion implantation and by oxidation of the bulk-Si. For annealing temperatures of 1100 °C, Pr silicate nanoclusters were observed consisting of Pr9.33Si6O26 or Pr2Si2O7. These silicates were the dominating and most stable Pr compounds. The interfaces between Pr silicate and the crystalline Si were atomically abrupt after high-temperature annealing. Pr silicide (PrSi2) was detected for lower annealing temperatures such as 900 °C and for higher annealing temperatures in minor fraction also in samples with enhanced O content. Pr oxide (Pr2O3), the promising high-k material, was not definitely verified. In ion beam synthesis, the energy related to structural reordering during solid-state compound formation is a parameter that controls the proceeding processes in addition to other parameters like chemical reactivity and the compound interface matching.