Anisotropy, i.e., the dependence of structure and properties on direction in space, is the most striking characteristic of crystals. Anisotropy is a result of the discrete nature of the crystal lattice, and it is the characteristic which distinguishes the crystalline state from another solid state of matter, the amorphous. The anisotropy of the structure and properties of crystals (this can be called their 'internal anisotropy') is also reflected in their external structure, i.e., morphology. The reflection is, however, non-linear: properties such as mechanical hardness ... do not change strongly (typically several tens of percents, depending on direction) while the morphology ... : the linear sizes in different directions of individual crystals often differ by several multiples or even several orders of magnitude, depending on the symmetry of the crystalline lattice and/or of the crystal prehistory. The enhanced anisotropy of morphology is, as a rule, a result of growth kinetics of different crystalline faces; it reflects a non-linear character of the kinetic laws of growth. This book is devoted to high morphological anisotropy. No strict classification of highly-anisotropic crystals exists. However some typical forms, or habits, can be singled out: first, whiskers (or needles, or fibers) as quasi-one-dimensional crystals, and second, platelets as quasi-two-dimensional crystals.

Growth of Crystals, Volume 21 presents a survey, with detailed analysis, of the scientific and technological approaches, and results obtained, by leading Russian crystal growth specialists from the late 1990's to date.

The volume contains 16 reviewed chapters on various aspects of crystal and crystalline film growth from various phases (vapour, solution, liquid and solid). Both fundamental aspects, e.g. growth kinetics and mechanisms, and applied aspects, e.g. preparation of technically important materials in single-crystalline forms, are covered.

A large portion of the volume is devoted to film growth, including film growth from eutectic melt, from amorphous solid state, kinetics of lateral epitaxy and film growth on specially structured substrates. An important chapter in this section covers heteroepitaxy of non-isovalent A3B5 semiconductor compounds, which have important applications in the field of photonics.

The volume also includes a detailed analysis of the structural aspects of a broad range of laser crystals, information that is invaluable for successfully growing perfect, laser-effective, single crystals.

Present-day scienceand technology have become increasingly based on studies and applications of thin films. This is especiallytrue of solid-state physics, semiconduc tor electronics, integrated optics, computer science, and the like. In these fields, it is necessary to use filmswith an ordered structure, especiallysingle-crystallinefilms, because physical phenomena and effects in such films are most reproducible. Also, active parts of semiconductor and other devices and circuits are created, as a rule, in single-crystal bodies. To date, single-crystallinefilms have been mainly epitaxial (or heteroepitaxial); i.e., they have been grown on a single-crystalline substrate, and principal trends, e.g., in the evolution of integrated circuits (lCs), have been based on continuing reduction in feature size and increase in the number of components per chip. However, as the size decreases into the submicrometer range, technological and physical limitations in integrated electronics become more and more severe. It is generally believed that a feature size of about 0.1um will have a crucial character. In other words, the present two-dimensional ICs are anticipated to reach their limit of minimization in the near future, and it is realized that further increase of packing density and/or functions might depend on three-dimensional integration. To solve the problem, techniques for preparation of single-crystalline films on arbitrary (including amorphous) substrates are essential."

Present-day scienceand technology have become increasingly based on studies and applications of thin films. This is especiallytrue of solid-state physics, semiconduc tor electronics, integrated optics, computer science, and the like. In these fields, it is necessary to use filmswith an ordered structure, especiallysingle-crystallinefilms, because physical phenomena and effects in such films are most reproducible. Also, active parts of semiconductor and other devices and circuits are created, as a rule, in single-crystal bodies. To date, single-crystallinefilms have been mainly epitaxial (or heteroepitaxial); i.e., they have been grown on a single-crystalline substrate, and principal trends, e.g., in the evolution of integrated circuits (lCs), have been based on continuing reduction in feature size and increase in the number of components per chip. However, as the size decreases into the submicrometer range, technological and physical limitations in integrated electronics become more and more severe. It is generally believed that a feature size of about 0.1um will have a crucial character. In other words, the present two-dimensional ICs are anticipated to reach their limit of minimization in the near future, and it is realized that further increase of packing density and/or functions might depend on three-dimensional integration. To solve the problem, techniques for preparation of single-crystalline films on arbitrary (including amorphous) substrates are essential."

For 50 years the Fedorov Institute of Crystallography, Mineralogy, and Petrography at Leningrad Mining Institute has held annual memorial meetings for E. S. Fedorov. Immediate ly after the jubilee meeting (May 21-24, 1969), the Fedorov All-Union Symposium on Crystal Growth was held, and the proceedings of that symposium constitute Volume 9 of Growth of Crystals. The symposium surveyed the advances made in the USSR in those aspects of growth con cerned mainly with morphology and structure in natural crystals or closely related artificial ones, work which confirmed their relation to E. S. Fedorov and to mineralogical crystallogra phy. Crystallography is one of the older branches of natural science but has recently under gone a striking rejuvenation on account of new methods and new concepts. Photogoniometric methods have been developed in goniometry, while crystal optics has found new lines of ad vance in electrooptics and techniques in the ultraviolet and far infrared regions. Morphologic studies now use a vast range of techniques, from the hand lens to the electron microscope or cinemicrography. X-ray analysis is steadily becoming more automatic, and fast computers are used with accelerated methods of structure interpretation. Crystal growth is one of the younger divisions of crystallography; previously t it had been of interest only in experimental mineralogy, but now it is an important branch of science and technology with close relations to industry.

The present volume of this series, following the tradition of the previous volumes, covers three major lines of research on crystallization: growth from vapor and epitaxy, growth from solution, and growth from melt. As in the previous volumes, preference is given to papers that provide original results and reviews of results obtained by the authors and those from published sources, although some of the papers are either purely original or purely of review character. The first section deals with crystal growth from vapor and epitaxy and contains three papers. One of them, on artificial epitaxy, discusses and reviews published results from the last three years in this rapidly developing area. The results are used in outlining mechanisms for oriented film growth on amorphous substrates. Another paper in this section deals with classical epitaxy, namely oriented growth on single-crystal substrates, where some important conclusions are drawn from the growth of gallium nitride films on sapphire, which concern the orientation relationships in that pair of substances. The last paper in the section deals with film growth under ion bombardment (the corresponding techniques in film crystallization have already advanced from theory to practical applications).

Anisotropy, i.e., the dependence of structure and properties on direction in space, is the most striking characteristic of crystals. Anisotropy is a result of the discrete nature of the crystal lattice, and it is the characteristic which distinguishes the crystalline state from another solid state of matter, the amorphous. The anisotropy of the structure and properties of crystals (this can be called their 'internal anisotropy') is also reflected in their external structure, i.e., morphology. The reflection is, however, non-linear: properties such as mechanical hardness ... do not change strongly (typically several tens of percents, depending on direction) while the morphology ... : the linear sizes in different directions of individual crystals often differ by several multiples or even several orders of magnitude, depending on the symmetry of the crystalline lattice and/or of the crystal prehistory. The enhanced anisotropy of morphology is, as a rule, a result of growth kinetics of different crystalline faces; it reflects a non-linear character of the kinetic laws of growth. This book is devoted to high morphological anisotropy. No strict classification of highly-anisotropic crystals exists. However some typical forms, or habits, can be singled out: first, whiskers (or needles, or fibers) as quasi-one-dimensional crystals, and second, platelets as quasi-two-dimensional crystals.