In situ analysis of the room-temperature epitaxial growth of CeO2 ultrathin films on Si (111) by coaxial impact-collision ion scattering spectroscopy

Abstract

The room-temperature epitaxial growth of CeO2 films on Si(111) substrates was examined in situ by combined use of a coaxial impact-collision ion scattering spectroscopy (CAICISS) and the laser molecular beam epitaxy (laser MBE). It was found that the crystal quality of CeO2 ultrathin films (∼3 nm thick) as-grown in UHV (∼10−9 Torr) could be improved remarkably by a few minutes of O2 gas exposure (∼10−5 Torr) at room temperature. A three-fold symmetry in the Ce signal intensity of azimuth rotational CAICISS spectra, which exhibited the type-B epitaxial growth ([1̄10]CeO2‖[11̄0]Si), was observed for the films thicker than about 1 nm.

Silicate-free growth of high-quality ultrathin cerium oxide films on Si(111)

“…The strong intensity observed at L ≈ 1 3 and L ≈ 4 3 (both denoted B in the figure) correspond to the (111) and (202) Bragg peaks (bulk coordinates), respectively, for B-oriented cubic cerium oxide, hence indicating the presence of a stacking fault at the interface, which has already been observed for ceria growth on H-passivated Si(111). 30 However, the discernible peak at L 2 3 suggests the coexistence of domains exhibiting regular, A-type stacking and can be associated with the (020) reflection, which is allowed for the fluorite structure (Fm3m) but forbidden for the diamond structure (Fd3m). It should be noted that the pronounced modulations of the diffracted intensity in the vicinity of the (01 corroborating the findings from the analysis of the (00L) CTR data.…”

Orientation selective epitaxial growth of CeO2 layers on Si(1 0 0) substrates using reactive DC magnetron sputtering with substrate bias

“…For applications to silicon technology, epitaxial growth of CeO 2 thin films on Si substrates has been studied, where a great deal of effort has been devoted to make use of close epitaxial relations of CeO 2 with silicon: both materials have cubic symmetry and a lattice mismatch parameter between them is a very small value of 0.35%. Epitaxial growth of CeO 2 layers on Si substrates has been studied for the application to microelectronics [1][2][3][4][5][6][7][8][9]. Although CeO 2 (1 1 1) layers grow on Si(1 1 1) substrates at very low temperatures, such as room temperature with excellent crystallinity [1][2][3][4][5][6][7], epitaxial growth on Si(1 0 0) substrates requires higher growth temperature and has strong tendency to grow with (1 1 0) orientation [1,8,10].…”

“…Epitaxial growth of CeO 2 layers on Si substrates has been studied for the application to microelectronics [1][2][3][4][5][6][7][8][9]. Although CeO 2 (1 1 1) layers grow on Si(1 1 1) substrates at very low temperatures, such as room temperature with excellent crystallinity [1][2][3][4][5][6][7], epitaxial growth on Si(1 0 0) substrates requires higher growth temperature and has strong tendency to grow with (1 1 0) orientation [1,8,10]. Much efforts have been devoted in obtaining single crystalline (1 1 0)-layers by preventing double domain structure formation using miscut substrates and lowering of epitaxial growth temperature by electron beam assistance during evaporation [11][12][13].…”

Oxygen radical irradiation effect in reactive magnetron sputtering for orientation selective epitaxial growth of layers on Si(100) substrates

“…Epitaxial growth of CeO 2 layers on Si substrates has been studied for the application to microelectronics, due to its advantageous properties, such as high dielectric constant, chemical stability, transmission in the visible and infrared regions and highly efficient ultra-violet absorption [1][2][3][4][5][6][7][8][9][10]. Many works have showed that epitaxially grown CeO 2 layers on Si(1 0 0) substrates have (1 1 0) orientation and require high growth temperature [1,7,10].…”