The impact of annealing and evaporation of crystals on their surface composition

Abstract

Auger electron spectroscopy and mass spectrometry have been used to investigate the elemental composition of single-crystalline LiNbO 3 surfaces subjected to annealing and evaporation in vacuum and to analyse the evaporation products. We found three distinct temperature regimes, within which the surface composition of LiNbO 3 undergoes different changes: outgassing (T = 300-650 K); surface segregation of Li and O (T = 650-1150 K); and evaporation of Li, O 2 and LiO (T 1150 K). The evaporation of Nb becomes noticeable only at temperatures close to the Curie temperature (1483 K).

Ferroelectric polarization dependent interactions at Pd–LiNbO3(0001) interfaces

“…The local atomic structure and the types and concentrations of surface defects on each surface, however, may still be dependent on the polarization orientation. The conclusion that the surfaces had similar compositions is consistent with that reported previously by Lushkin et al 23 and Yun et al 24 For example, Lushkin et al 23 also used AES to characterize the composition of LiNbO 3 ͑0001͒ and found that the c+ and c− surfaces had similar composi- tion and except for the loss of a small amount of oxygen the composition remained constant for annealing temperatures up to 700 K. For higher annealing temperatures, Li depletion was observed and occurred more rapidly on the c+ surface relative to the c− surface. 700 K was used as the annealing temperature in the present study in order to limit the amount of Li desorption.…”

“…As noted above, the AES results obtained in this study and those reported previously by Lushkin et al 23 indicate that the c+ and c− surfaces have similar compositions. This conclusion is consistent with a more detailed study of the surface structure of LiNbO 3 ͑0001͒ reported by Yun et al 24 In that study based on x-ray photoelectron spectroscopy ͑XPS͒, ion scattering spectroscopy ͑ISS͒, and TPD data, it was also concluded that the c+ and c− surfaces prepared by annealing in oxygen in UHV had similar compositions and both exhibited ͑1 ϫ 1͒ low energy electron diffraction patterns indicating that they had similar structures.…”

Thickness, humidity, and polarization dependent ferroelectric switching and conductivity in Mg doped lithium niobate

“…50 Local domain nucleation and propagation requires stabilization through screening of surface bound charge, which can be provided externally by reorientation of charge in electrodes and adsorbed ions, and also internally through bulk conductivity and charge injection. 25,28,46,51 Polarization dependent dielectric surface layers 50,52 can inhibit external screening, thus changing conditions for domain evolution. 49,51,53 However, the results suggest only a minor influence of such "dead" layers as (i) domain patterns clearly depend on external conditions such as humidity and (ii) external screening is minimized in dry conditions for which the polarization dependence was observed.…”

Lithium niobateX-cut,Y-cut, andZ-cut surfaces fromab initiotheory

“…The subtle balance between the ionic and covalent character of the metal-oxygen bonds can be affected by small temperature changes during the growth, resulting in an inversion of the polarization direction. 14 Among the technologically relevant surfaces, the LN Z cut is most intensively investigated, both from experiment [15][16][17][18] as well as ab initio theory. 19,20 Density-functional theory ͑DFT͒ investigations predict stoichiometric differences between positive and negative surfaces.…”