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Volume 1 of Point Defects in Solids has as its major emphasis defects in ionic solids. Volume 2 now extends this emphasis to semiconductors. The first four chapters treat in some detail the creation, kinetic behavior, inter actions, and physical properties of both simple and composite defects in a variety of semiconducting systems. Also included, as in Vol. 1, are chapters on special topics, namely phonon-defect interactions and defects in organic crystals. Defect behavior in semiconductors has been a subject of considerable interest since the discovery some twenty-five years ago that fast neutron irradiation profoundly affected the electrical characteristics of germanium and silicon. Present-day interest has been stimulated by such semiconductor applications as solar cell power plants for space stations and satellites and semiconductor particle and y-ray detectors, since in both radiation damage can cause serious deterioration. Of even greater practical concern is the need to understand particle damage in order to capitalize upon the develop ing technique of ion implantation as a means of device fabrication. Although the periodic international conferences on radiation effects in semiconductors have served the valuable function of summarizing the extensive work being done in this field, these proceedings are much too detailed and lack the background discussion needed to make them useful to the novice.
Lattice defects of organic molecular crystals affect their optical or electrical properties by changing the local energy structure. Lattice defects also playa very important role in the chemical and physical properties, for example, as an active site of a catalyst or an initiating point of a solid state reaction. However, very little has been reported on the defect structure of real organic crystals. In the past ten years it became clear that the origin and the structure of the defects depend on the geometrical and chemical nature of the building units of the crystal, the molecules. Molecular size, form and anisotropy, charge distribution, etc. cause the characteristic structure of the defect. Accordingly, a defect structure found in one compound may not be found in others. The defect structure of an organic crystal cannot be defined solely by the displacement of the molecular center from the normal lattice site. A rotational displacement of a molecule is frequently accompanied by a parallel shift of the molecular center. In addition to the usual geometrical crystallographic defects, chemical defects are important too which originate, for example, from differences in the substitution sites of molecules carrying side groups. In order to reveal such defect structures, direct imaging of molecules by high resolution electron microscopy is the only direct method.
Spectroscopy of Defects in Organic Crystals presents a masterly summary of the widespread and voluminous literature on the subject, presenting theoretical and experimental investigations of electron and vibronic optical spectra of organic crystals. Electronic states of defects combine to form crystal near-to-band and band levels. These are discrete states in the vicinity of exciton bands, surface and dislocational excitons, etc. Some studies have expressed dissimilar or even conflicting opinions about the nature of observed phenomena. In the choice of the material, preference has been given to phenomena which have received a theoretical interpretation. Some attention is paid to observations which are not completely understood and also to effects predicted but not yet confirmed. The monograph will be useful for scientists as well as undergraduate and postgraduate students of solid state physics.
Volume 1 of Point Defects in Solids has as its major emphasis defects in ionic solids. Volume 2 now extends this emphasis to semiconductors. The first four chapters treat in some detail the creation, kinetic behavior, inter actions, and physical properties of both simple and composite defects in a variety of semiconducting systems. Also included, as in Vol. 1, are chapters on special topics, namely phonon-defect interactions and defects in organic crystals. Defect behavior in semiconductors has been a subject of considerable interest since the discovery some twenty-five years ago that fast neutron irradiation profoundly affected the electrical characteristics of germanium and silicon. Present-day interest has been stimulated by such semiconductor applications as solar cell power plants for space stations and satellites and semiconductor particle and y-ray detectors, since in both radiation damage can cause serious deterioration. Of even greater practical concern is the need to understand particle damage in order to capitalize upon the develop ing technique of ion implantation as a means of device fabrication. Although the periodic international conferences on radiation effects in semiconductors have served the valuable function of summarizing the extensive work being done in this field, these proceedings are much too detailed and lack the background discussion needed to make them useful to the novice.
Lattice defects of organic molecular crystals affect their optical or electrical properties by changing the local energy structure. Lattice defects also playa very important role in the chemical and physical properties, for example, as an active site of a catalyst or an initiating point of a solid state reaction. However, very little has been reported on the defect structure of real organic crystals. In the past ten years it became clear that the origin and the structure of the defects depend on the geometrical and chemical nature of the building units of the crystal, the molecules. Molecular size, form and anisotropy, charge distribution, etc. cause the characteristic structure of the defect. Accordingly, a defect structure found in one compound may not be found in others. The defect structure of an organic crystal cannot be defined solely by the displacement of the molecular center from the normal lattice site. A rotational displacement of a molecule is frequently accompanied by a parallel shift of the molecular center. In addition to the usual geometrical crystallographic defects, chemical defects are important too which originate, for example, from differences in the substitution sites of molecules carrying side groups. In order to reveal such defect structures, direct imaging of molecules by high resolution electron microscopy is the only direct method.