Surface texture evolution of polycrystalline and nanostructured films: RHEED surface pole figure analysis

Abstract

In this topical review, we outline the construction of a reflection high-energy electron diffraction (RHEED) surface pole figure from a polycrystalline film by recording multiple RHEED patterns as the substrate is rotated around the surface normal. Due to the short penetration depth of electrons, the constructed pole figure is a surface pole figure. It is in contrast to the conventional x-ray pole figure which gives the average texture information of the entire polycrystalline film. Examples of the surface pole figure construction processes of a fibre texture and a biaxial texture are illustrated using Ru vertical nanorods and Mg nanoblades, respectively. For a biaxially textured film, there often exists an in-plane morphological anisotropy. Then additional intensity normalization must be applied to compensate for the effects of anisotropic morphology on RHEED surface pole figure construction. Rich information on the texture evolution, such as the change in the tilt angle of the texture axis, has been obtained from the in situ study of oblique angle vapour deposition of Mg nanoblades using RHEED surface pole figures. Finally we make a comparison between the RHEED surface pole figure and the conventional x-ray pole figure techniques.

Biaxially oriented CaF2 films on amorphous substrates

“…The texture of the nanorod films was evaluated through X-ray diffraction and X-ray pole figure analyses. X-ray pole figures were obtained by collecting multiple diffraction patterns using an area detector in a Bruker D8 Discover diffractometer (Cu target, wavelength ¼ 0.15405 nm) [1]. Transmission electron microscopy (TEM, model JEOL 2010, 200 kV) was used to examine how the texture evolves at different stages of growth in more detail.…”

“…The biaxially textured films are not exactly single crystals, but they have strongly preferred crystallographic orientations in both the out-of-plane and in-plane directions [1,2]. Biaxial films have been used as buffer layers for subsequent growth of highly oriented (both the out-of-plane and in-plane) high T c superconducting films to achieve high current density.…”

Perspectives on oblique angle deposition of thin films: From fundamentals to devices

“…For the presentation of the majority of the results, we have assumed that readers are already familiar with common material characterization techniques such as electron microscopy and X-ray diffraction. However, some mention has been made on less conventional methods such as grazing incidence small-angle X-ray scattering (GISAXS) [33] and reflection high-energy electron diffraction (RHEED) [34] that have been used recently in the study of OAD thin films, and which have contributed to deepening the understanding of their properties. Contrary to the organization typically adopted by other reviews into OAD thin films, where basic properties such as their porosity, nanocolumnar shape or bundling association are correlated to their tilted nanocolumnar microstructure, we have opted to include a discussion on these features in Section 3.…”

Growth of CdTe Films on Amorphous Substrates Using CaF2 Nanorods as a Buffer Layer

“…Similar analysis has been conducted for Mg nanoblades and Ru nanorods. [9][10][11] In order to study the epitaxial relationship between the CdTe film and the CaF 2 , we used cross-sectional TEM analysis. The cross-sectional TEM image shown in Fig.…”