Measurement of Axisymmetric Crystallographic Texture
Mark D. Vaudin
Crystallographic texture has for many years been the fiefdom of metallurgists and geologists, who have developed elegant methodologies for the analysis of highly complex textures and texture evolutions. Over the past two decades, the importance and relevance of texture in a variety of materials systems and applications has become better appreciated. Thin film technologies, especially where the materials involved have anisotropic properties and where texture can be induced in layers as thin as a few nanometers, have required that researchers were aware of texture and could make measurements to characterize it. The textures that occur naturally in thin films are almost invariably of axial symmetry (also known as fiber texture) and are often very sharp, and there is a need to discriminate between different levels of sharp texture. Texture is no longer the preserve of the specialist since materials scientists in many areas of research and product development often encounter texture, and need to be able to measure it and understand its implications. The x-ray tool of the metallurgist or geologist, the four-circle goniometer, is frequently not available to perform these characterizations, and a powder diffractometer is often the best tool available. There may in fact be reasons why a diffractometer equipped with a four-circle goniometer is not necessarily the most suitable for the required texture measurements. This guide aims to help the researcher exploit the available tools to maximize the texture information that can be obtained. It is the result of many years of measuring texture in a variety of semiconductor, ceramic and metal systems.