Postdeposition annealing induced transition from hexagonal Pr(2)O(3) to cubic PrO(2) films on Si(111)

作者：Weisemoeller T^*; Bertram F; Gevers S; Greuling A; Deiter C; Tobergte H; Neumann M; Wollschlaeger J; Giussani A; Schroeder T

来源：Journal of Applied Physics, 2009, 105(12): 124108.

DOI：10.1063/1.3152796

Films of hexagonal praseodymium sesquioxide (h-Pr(2)O(3)) were deposited on Si(111) by molecular beam epitaxy and thereafter annealed in 1 atm oxygen at different temperatures, ranging from 100 to 700 degrees C. The films of the samples annealed at 300 degrees C or more were transformed to PrO(2) with B-oriented Fm (3) over barm structure, while films annealed at lower temperatures kept the hexagonal structure. The films are composed of PrO(2) and PrO(2-delta) species, which coexist laterally and are tetragonally distorted due to the interaction at the interface between oxide film and Si substrate. Compared to PrO(2), PrO(2-delta) has the same cubic structure but with oxygen vacancies. The oxygen vacancies are partly ordered and increase the vertical lattice constant of the film, whereas the lateral lattice constant is almost identical for both species and on all samples. The latter lattice constant matches the lattice constant of the originally crystallized hexagonal praseodymium sesquioxide. That means that no long range reordering of the praseodymium atoms takes place during the phase transformation.

• 出版日期2009-6-15