Strontium silicide termination and silicate epitaxy on (001) Si

Abstract

We have investigated the epitaxial growth of (Sr,Ba)-based oxides on SrSi2-terminated (001) Si using laser-molecular beam epitaxy. Reflection high-energy electron diffraction (RHEED) confirms the formation of a commensurate submonolayer of (Ba,Sr)Si2 when strontium and barium ablation targets are used as the metal sources. Stability of the silicide RHEED peak intensity between laser ablation pulses indicates that the submonolayer SrSi2 coverage is relatively stable during formation despite the required high temperatures. While the subsequent growth of BaO via Ba metal ablation and O2 flux on the SrSi2-terminated surface is favored at low temperatures, the formation of an epitaxial silicate is observed for oxide formation at temperatures above 550 °C. X-ray diffraction confirms that the Ba2SiO4 film formed with elevated temperature oxidation is in-plane aligned. These results suggest that while epitaxial BaO can be realized on SrSi2-terminated Si, the interface may be susceptible to silicate formation upon thermal treatment. These results also demonstrate that laser-molecular beam epitaxy can be effective in achieving submonolayer surface coverage specifically for terminating silicon for oxide epitaxy.

Interface structure and phase of epitaxial SrTiO3 (110) thin films grown directly on silicon

“…11 Extensive research has been carried out on the growth of STO ͑001͒ on Si ͑001͒ with various single buffer layers and/or multi-buffer layers. 4,[12][13][14][15] Recently, both theoretical and experimental studies have shown that the resulting interfacial structures between silicon and the grown STO thin films depend upon the details of deposition conditions and specific growth sequences. [16][17][18][19] It suggests that differing synthesis routes may lead to epitaxial STO films with different atomic scale structure of the interface.…”

Formation of alkaline-earth template layers on Ge(100) for oxide heteroepitaxy: Self-organization of ordered islands and trenches

“…4,5,9,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] The key question regarding these phases is whether they are simple alkaline-earth adatom structures or more complex surface alloys. Adatom models 8,28 fail to reproduce STM images of the (3×2) phase, 17,25,27 while alloy models 9,10,25 require significant Si dimer movement to occur at temperatures well below those typically required for mass transport on Si surfaces.…”

Epitaxial lanthanide oxide thin films on Si for high-k gate dielectric application: Growth optimization and defect passivation

“…32 This finding agrees to an earlier report by Norton et al, where the formation of silicide like surface structure was also associated with the appearance of additional 1/3-order reflections on a (2 Â 1) reconstructed surface during Sr deposition on Si(100). 33 With increase in the Nd 2 O 3 layer thickness of above 1 nm the spectra exhibit additional peaks at higher binding energies which could be attributed to the different kinds of silicate like bonds. 34 neodymium 3d 5/2 core-level spectra also supports the silicide-like bond formation at the interface during initial stage of the oxide layer growth (Fig.…”