Single crystals of 2H SiC were observed to undergo phase transformations at temperatures as low as 400 C. Some 2H crystals transformed to a structure with one-dimensional disorder along the crystal c axis. Others transformed to a faulted cubic/6H structure. The transformation is time and temperature dependent and is greatly enhanced by dislocations. Observations indicate that the transformation takes place by means of a slip process perpendicular to the c axis. Cubic SiC crystals were observed to undergo a solid state transformation above 1400 C.

The report discusses the growth of beta silicon carbide by the hydrogen reduction of methyl trichlorine onto carbon substrates at 1500C. It is shown that alpha inclusions present are the rare 2H (Wurtzite) modification of silicon carbide and that their presence resulted from a vapor-liquid-solid growth mechanism which was dominated by impurities in the substrate. By carefully cleaning the substrate and purifying the methyltrichlorosilane, the alpha inclusions were eliminated. The 2H alpha crystals were then deliberately grown by introducing selected impurities locally on the substrate. Beta crystals were also intentionally grown by the vapor-liquid-solid technique by introducing appropriate impurities. Growth of beta silicon carbide from the melt is also briefly discussed. (Author).

The present volume continues the tradition of the preceding volumes. covering a wide range of crystal growth problems and treating aspects of critical importance for crystalliza tion. Changes in this field of knowledge have. however, changed the criteria for selection of papers for inclusion in this series. The increasing role of crystals in science and technology is even more apparent today. The study and utilization of these highly perfect objects of nature considerably facilitates progress in the physics and chemistry of solids. quantum electronics, optics, microelectron ics, and other sciences. The demand for crystals and crystal devices has grown steadily and has led to the emergence and rapid growth of the single crystal industry (we can safely saythat the state ofthe art in this industry is indicative ofthe overall scientific and technolo- cal potential of a country). At the same time, the introduction of crystallization techniques into other industries is gaining ever-increasing importance. To illustrate this last state ment, we can mention the fabrication of textured structural materials and direct methods of metal reduction in ores by using chemical vapor transport techniques. Crystallization tech ll niques progress both in "width" and in "depth : traditional methods are modernized. and novel techniques appear, some of them at the junction of the already existing technologies (for example, flux growth of crystals, growth from vapor with participation of the liquid phase, etc. ).

A variety of nanomaterials have excellent optoelectronic and electronic properties for novel device applications. At the same time, and with advances in silicon integrated circuit (IC) techniques, compatible Si-based nanomaterials hold promise of applying the advantages of nanomaterials to the conventional IC industry. This book focuses not only on silicon nanomaterials, but also summarizes up-to-date developments in the integration of non-silicon nanomaterials on silicon. The book showcases the work of leading researchers from around the world who address such key questions as: Which silicon nanomaterials can give the desired optical, electrical, and structural properties, and how are they prepared? What nanomaterials can be integrated on to a silicon substrate and how is this accomplished? What Si-based nanomaterials may bring a breakthrough in this field? These questions address the practical issues associated with the development of nanomaterial-based devices in applications areas such as solar cells, luminous devices for optical communication (detectors, lasers), and high mobility transistors. Investigation of silicon-based nanostructures is of great importance to make full use of nanomaterials for device applications. Readers will receive a comprehensive view of Si-based nanomaterials, which will hopefully stimulate interest in developing novel nanostructures or techniques to satisfy the requirements of high performance device applications. The goal is to make nanomaterials the main constituents of the high performance devices of the future.