Polycrystalline thin films phase identification
These types of samples are produced using various deposition methods and range in thickness from 1 nm to several microns and on different type of substrates (amorphous, crystalline, single crystalline). The experiment is similar to collecting powder diffraction pattern with the additional challenge of a small diffraction volume which can be masked by the strong signal of the substrate. The high intensity provided by the rotating anode and the reduced collection time using the Hypix 2D detector makes it possible to perform phase identification routinely.
X-ray reflectivity
Accurate knowledge of the thickness of thin films is often a requirement when integrated in a process for device fabrication or measuring physical properties. X-ray reflectivity is a non-destructive method that allows the measurement of the thickness of layers and multilayers of smooth nanostructure. Additional information such as density, interface roughness and inter-diffusion can be gained by modelling the specular x-ray reflectivity.
Texture and pole figure
The process used to prepare nanoscale and thin film structure can lead to different microstructures which can influence the property of the material (e.g. conductivity, surface reactivity, device lifetime …). It is possible to determine the texture of a nanostructure by measuring pole figure using XRD. In the case of highly oriented and epitaxial thin films biaxial texture is observed and the measurement of pole figures can be used to determine the relative orientation of the unit-cell with respect to the substrate and the multiplicity of the pole reflection can inform on the symmetry of the material.
Epitaxial thin films phase analysis
Similar to the development of polycrystalline films, the assessment of epitaxial thin films require capability similar to (a), but the oriented nature of the samples add another characterisation degree of freedom in assessing the crystalline quality of the sample (rocking curve).
Reciprocal space mapping
When producing epitaxial thin film of a new material, RSM is used to determine epitaxial relationship between the film and the substrate and assess the possible strain applied to the layer. In conjunction with the capability (d), the measurement of RSMs on epitaxial thin films is used routinely to determine the in-plane strain of the films and to calculate the lattice parameter of the new materials produced.
In-plane diffraction
With standard diffraction geometries, such as the Bragg-Brentano geometry, lattice planes that are parallel to the sample surface are probed. The addition of an in-plane scattering arm affords to measure lattice planes that are (nearly) perpendicular to the sample surface, which are inaccessible by other techniques and control the penetration depth of the beam is limited to within about 100 nm of the surface.
Glancing incidence x-ray diffraction
In conventional x-ray diffraction experiment with large incident angles, the penetration depth of the beam is large and the bulk of the material is probed. To perform surface sensitive experiments, glancing incidence x-rays are needed. At an incident angle near or below the critical angle for total reflection, the incident beam is evanescent and penetrates only the top 100 Å or less into the surface. This capability will therefore benefit the research projects involving polycrystalline thin films grown on crystalline by reducing the contribution of the substrate in the diffraction pattern. It will also benefit project where controlling interfaces is vital and add the possibility to perform depth profile analysis.
High throughput screening
The high photon flux from the rotating anode and the two-dimensional detector will not only allow reduced measurement time, but additional beam conditioning and automated stage will add another capability in allowing design of experiment for process optimisation and combinatorial growth.
Variable temperature measurements
The ancillary option of a heating stage in a thin film configuration will also allow phase transition studies at elevated temperature by following specific Bragg reflections that are not necessarily out-of-plane.
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