The birth of the modern age of semiconductor electronics in the 1950s required the production of single crystals from the melt. In the early years of this technology, crystals exhibited non-uniform distributions of chemical and structural defects, which directly affected devices produced from this material. Uniform distribution and control of dopants, unintentional impurities, and native defects were identified Lis critical requirements for continued advances in device technology. However, since at that time fundamental understanding of cause and effect relationships between crystal growth parameters and the ultimate properties of the materials produced was absent, such desirable properties were unattainable. Nevertheless, it was recognized that segregation plays a key role in the creation of non-uniformities. Macrosegregation, a consequence of the directional solidification process, is generally controlled by diffusion and convective melt flows. Microsegregation is governed by local perturbations at the crystal-melt interface. Time-dependent thermal and melt velocity fields at the crysltal-melt interface impact the microscopic rate of growth and the solute diffusion boundary layer. Identification of the fundamental parameters that govern axial and radial macro- and microsegregation during bulk semiconductor crystal growth was the research focus during the early years. Key contributions were made by Prof. August F. Witt and his research group. One of the major contributions was the development of quantitative analytical tools for characterization of the crystal growth process. These tools provided the foundation for understanding the origin and nature of segregation phenomena during crystal growth from the melt. This paper is a brief review of his work. (C) 2004 Elsevier B.V. All rights reserved.