Progress in the growth and research of crystals for wide-gap semiconducting materials

The feasibility of a sublimation sandwich method for controlled growth of single crystals and epitaxial layers of different SiC and GaN polytypes is demonstrated. The controlled production of pure (n _i <10¹⁶ cm⁻³) and heavily-doped crystals and epitaxial layers of these materials has made it possible to study their semiconducting parameters in detail and to identify the nature of a number of the most important impurity centers. It is shown for the example of SiC that the typically high chemical-binding energy of atoms in these compounds is the reason for the formation of stable metastable compounds, among them associations and clusters that include intrinsic defects which have a significant effect on the properties of the material. Clusters formed on the surface can serve as seeds for different polytypes during crystal growth. Fiz. Tverd. Tela (St. Petersburg) 41, 822–825 (May 1999)