1 Introduction

Most semiconductor optoelectronic and many microelectronic devices are fabricated on heterostructures which consist of layers of different materials but the same crystal structure. In this case advanced epitaxial growth techniques are needed. But even in the case of well-developed epitaxial growth technologies device parameters can be degraded if the substrate material quality or processing is poor. Therefore wafer fabrication technology is equally important for state-of-the-art semiconductor device manufacturing. A comparison of liquid and gas phase growth techniques shows that liquid phase methods provide low cost fabrication of large single crystals and are normally the method of choice for large scale production of crystals for further wafer manufacturing. Unfortunately it is hard to employ this method for certain semiconductors since due to specific phase diagrams extremely high pressures are needed to prevent the decomposition of the source material at temperatures lower than the melting point. This problem exists for instance in...