Epitaxial growth of single crystalline lattice-matched Pr0.9Y1.1O3 on SrO-passivated Si (001): Growth orientation and crystallization tailoring by interface engineering

In this work, SrO buffer layers were employed as an interface engineering approach to realize single crystalline mixed ternary rare earth bixbyite oxide (RE₂O₃) films on Si (001) substrate. Single crystalline mixed Pr_xY_2-xO₃ (x=0-2) has been successfully grown on Si (111) (Ref. 7). However, the formation of such mixed oxide can only be realized at >750 °C, therefore when it is directly grown on Si (001) Pr_xY_2-xO₃ is polycrystalline due to the formation of an amorphous silicate or SiO₂ interfacial layer on Si (001). A 1/2 monolayer (ML) SrO buffer layer can effectively prevent the interface reaction thus it allows realizing single crystalline ternary mixed Pr_0.9Y_1.1O₃ films on Si (001). This fully lattice-matched RE₂O₃ film demonstrates 110 orientation on Si (001). Furthermore, SrO buffer layers are not only important to control the single crystallinity but also the growth orientation and crystallization behaviour of ternary RE₂O₃ films. A 111-oriented, phase separated Pr₂O₃-Y₂O₃ film was obtained under identical growth conditions by simply increasing the thickness of SrO buffer layer to 3 ML.