Structure and stability of PrO/Si(001) heterostructures grown by molecular beam epitaxy using a high temperature effusion source

Tinkham, B. P.*; Takahashi, Masamitsu; Jenichen, B.*; Watahiki, Tatsuro*; Braun, W.*; Ploog, K. H.*

The structure of epitaxially grown PrO on Si(001) has been investigated by grazing incidence X-ray diffraction and X-ray reflectivity. We report experimental results from measurements made in situ, after growth, and during annealing to determine the stability of PrO at temperatures relevant for complementary metal oxide semiconductor (CMOS) processing. PrO is evaporated and converted to PrO using an effusion source operating at 1970C. Two different phases of PrO have been identified in the as-grown films in addition to a silicate layer that forms upon nucleation at the Si interface. The cubic PrO nucleates as a single crystal and grows in greater proportion to the polycrystalline hexagonal PrO. The crystal structure of the as-grown film is stable during annealing up to about 800C at which point the PrO is consumed at the expense of the silicate phase.