Photonic crystals are industrially grown by Czochralski method, growth of new compositions is performed using a micro-pulling down method. Both of these methods are so-called crucible methods, which brings few fundamental limitations. There is a problem with crucible materials, because of very high materials reactivity at temperatures of the melting point of photonic single crystals, which is often higher than 2000°C. Such reactivity leads to the incorporation of crucible atoms into the crystal lattice of growing single-crystal. During growth, a protective Ar atmosphere is also needed to avoid degradation of the expensive crucibles, which, however, leads to oxygen vacancies in single-crystal lattice. The floating zone method is contactless and crucible-free, which allows the growth of single-crystals of higher purity and single crystals of materials with very high melting points as well as under pure oxygen atmosphere. At DCMP there are two floating zone furnaces, halogen and laser-diode one. The second is unique in many aspects.
We chose Nd:YAG as testing material for floating zone method growth as it can be grown in both furnaces. In the lecture, we would describe both furnaces. We will describe in detail the method of preparation of precursors and their development with respect to the stability of growth process and reproducibility of the quality of obtained single crystals. Next, we will focus on the individual parameters of the growth process and finally on the physical properties of the grown single-crystals.
The know-how of the Nd: YAG floating zone method growth is valuable for the growth of other compositions. The growth of different compositions and the subsequent comparison with crystals from industrial production is important for the evaluation of the floating zone method as a way for testing new compositions for industrially perspective materials