The temperature field created in a tube furnace by thermal radiation is described here with an easy to use model suitable for the determination of the axial and radial temperature profiles in the furnace chamber. Particular attention is paid to the radial temperature differences and their role in the evaporation-condensation processes-these differences ensure "contactless" crystal growth from the vapour at around 1100 K by preventing condensation on the ampoule wall. It is shown that the creation of radial temperature differences of a few degrees is achievable by interaction of the solid material with more distant zones of the furnace. The model has proved to be a tool for the description and control in self-selecting vapour growth as initially applied to IV-VI compounds and extended to II-VI wide bandgap compounds and, especially, their solid solutions. Broader use of the model is expected. (C) 2003 Elsevier B.V. All rights reserved.