Specific Process Knowledge/Characterization/XRD/Process Info: Difference between revisions
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==XRR== | ==XRR== | ||
With X-Ray Reflectivity measurements, it is possible to obtain information on thickness, density, and surface and interface roughness of thin films. The technique does not depend on crystal structure and can be used on both amorphous, poly-, and single-crystalline materials. | |||
For film thickness measurement, films up to around 100-300 nm can be measured depending on the material (thicker layers of lighter elements, thinner layers of heavy elements like Au). You are welcome to try it on thicker films, but please confirm the measurement the first time by use of other equipment. | |||
XRR is a special case of a Theta/2Theta measurement. You can see the optics used for the measurements and read more about the principles here: [[/The Principles of X-ray Reflectivity Analysis|The principles of X-ray reflectivity analysis (XRR)]] | |||
[[/The Principles of X-ray Reflectivity Analysis|The principles of X-ray reflectivity analysis (XRR)]] | |||
==In-Plane Measurements 2θχ or 2θχ/φ scans == | ==In-Plane Measurements 2θχ or 2θχ/φ scans == | ||
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Pole figures can be used to determine the orientation of a crystal. For polycrystalline materials, it is possible to determine if there is a preferred direction of the crystal grains. In a pole figure, a measurement of a predefined peek for the material is measured in the half sphere above the sample. This will result in a map of intensities in relation to the angles from the surface normal and along sample rotation. For instance if you have a single crystalline sample with a [0 0 1] surface and measure on the [1 1 1] lattice plane, you should find 4 peaks spaced 90° in beta and at 35.26° in alpha. | Pole figures can be used to determine the orientation of a crystal. For polycrystalline materials, it is possible to determine if there is a preferred direction of the crystal grains. In a pole figure, a measurement of a predefined peek for the material is measured in the half sphere above the sample. This will result in a map of intensities in relation to the angles from the surface normal and along sample rotation. For instance if you have a single crystalline sample with a [0 0 1] surface and measure on the [1 1 1] lattice plane, you should find 4 peaks spaced 90° in beta and at 35.26° in alpha. | ||
Peak angles can be calculated by simple vector calculations; however, | Peak angles can be calculated by simple vector calculations; however, we have made a [[Specific Process Knowledge/Characterization/XRD/Process Info/Pole Figure script|small MATLAB script]] calculating them for you. To use the script, open MATLAB and call the program with two vectors as input. First vector should be your surface orientation, second input the plane you measure on. For a [1 1 1] substrate surface and a [3 1 1] plane and a [0 0 1] substrate surface and a [1 3 3] plane, where the measurement planes are dependent on the 2theta angle, the command looks like this: | ||
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