IntroductionModern society features information processing on a large scale and is supported by information technologies, which require high-speed data processing and high-speed data transmission. From the viewpoint of materials science and engineering, this is supported by high-quality semiconductor crystals, produced from high-temperature melt processes, such as the Czochralski, the floating zone, Bridgman processes, and so on. In order to understand and control these high-temperature processes, computer modeling is one of the superior tools available. This shows us the physics of these processes and how to improve processes and products, as shown in Fig. 4.1 [1]. This has been made possible thanks to the year-by-year improvements in computer performance, and even turbulence flow can now be handled. In modeling equations for continuity, momentum, energy and the Maxwell equation are solved simultaneously. In order to calculate temperature, flow and pressure fields of a high-temperature process, the thermophysical properties of the molten state in particular are indispensable. A survey was carried out on the required thermophysical properties for silicon crystal growth processes and on thermophysical properties actually employed in modeling in Japan: see Fig. 4.2 and Table 4.1 [2][3][4]. Table 4.1 shows thermophysical properties employed in 44 papers. The scatter of the data is rather large; particularly for the temperature coefficient of surface tension, the difference is one order of magnitude. Historically, Glazov et al. [5] reviewed thermophysical properties of molten semiconductors not only for molten silicon but also for other compound molten semiconductors. However, modern society requires the development of new measurement techniques and improvements in the accuracy and precision of data. Iida and Guthrie [6] overviewed thermophysical properties of molten metals and methods for measurements; this is a good textbook for thermophysical property measurement of high-temperature melts. Figure 4.2 shows that thermal conductivity, specific heat capacity and surface tension are urgently required. Although thermal conductivity is required to calculate heat balance at the solid/liquid interface during crystal growth and is important to Crystal Growth Technology. Edited by Hans J. Scheel and Peter Capper