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X-ray thin film measurement techniques VII. Pole figure measurement

Summer 2011, Volume 27, No. 2
Keigo Nagao and Erina Kagam*

Since crystal orientation and the degree of preferred orientation in thin films have a great influence on the properties of thin film devices, it is crucial for thin film devices to control the preferred orientation texture of thin film materials for applications such as light-emitting devices, ferroelectric memory and transparent conductive film applications, etc.

The Electron Back Scatter Diffraction (EBSD) technique, combined with a Scanning Electron Microscope (SEM), has been a popular approach for determining crystallite orientation and distribution in the field of material science. Recently, this technique has become focused of great interest due to major improvements in the throughput speed of analysis, as well as its capability for inspections to the scale down to several tens to hundreds of nm.

On the other hand, the irradiation area on the sample surface in pole figure (PF) measurements with X-ray Diffraction (XRD) is φ 10 μm to 50 mm. The advantages of PF measurements by XRD are as follows: firstly, it allows the analysis of textural information of samples averaged over a large area/volume and, secondly, this measurement can be performed under ambient conditions or at high/low temperature by changing the atmospheric conditions.

In the process of texture analysis of materials, it is necessary to express the distribution of crystallite lattices in the coordinates of the external field, such as applied stress, magnetic field, etc. For most thin film cases, it would be the lattice of a single crystalline substrate.

In earlier articles in this series about thin-film analysis techniques, out-of-plane measurement and in-plane measurement techniques were explained in the 2nd and 4th articles. This article will explain the basics of the pole figure measurement/analysis technique using out-of-plane and in-plane measurement geometry, followed by their applications for thin films samples.


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