The paper highlights current understanding in defects and defect processes in Si and GaAs. How oxygen in Si and point defects in GaAs lead to a defect formation is described. It is emphasized that defects are no longer entities merely to be avoided, but sensitive probes of undetectable defects and defect processes. Further technological demands for higher levels of sophistication must join with the improvements in characterization methods. [J. Cryst. Soc. Jpn. 28, 61 (1986) ] .
Correlation between VLSI and crystal technology is comprehensively reviewed for crystallogra-phers who are not necessarily familiar to semiconductor devices. Questions such as “Why are VLSI devices produced by high-quality CZ Si single crystals?”and“Why is an epitaaial wafer necessary for VLSI?”are answered. Importance of wafer flatness in the fabrication of VLSI devices, and microdefects in CZ Si and their application to intrinsic gettering are also included. Moreover, it is emphasized that advanced techniques of material characterization, which will be indispensable to VLSI in the near future, are earnestly desired in the VLSI field. [J. Cryst. Soc. Jpn. 28, 72 (1986) ] .
Recent progress of SOI growth by electron beam recrystallization is described. Emphasis was placed on pseudo-line electron beam (PLEB) technique with lateral seeded epitaxy. Through computer simulation of the temperature distribution of the sample during electron beam irradiation, amplitude modulation of a high frequency oscillation wave is proved to be useful for obtaining large area SOI. Agglomeration of SOI near seed region can be suppressed by using a seed structure with tape-red edge and narrow seed width of 2 μm, which leads to realization of single crystalline SOI with well controlled crystallographic orientation. A large area SOI growth, 4 mm_??_, is successfully carried out. [J. Cryst. Soc. Jpn. 28, 83 (1986) ] .
Liquid-encapsulated Czochralski (LEC) grown, undoped GaAs exhibits high resistive, semiinsulating property and is very suitable for high performance GaAs IC's substrate with a direct ionimplantation technology. An FET threshold voltage, however, is strongly influenced by material properties. A close relationship between dislocations, native antisite defects AsGa and FET threshold voltage is briefly discussed, and it is demonstrated that dislocation-free GaAs exhibits a very uniform electrical properties desirable for GaAs ICs substrate.
Physical properties of point defects in III-V semiconductors, especially in GaAs, are discussed in view of their significant roles in device characteristics. As a representative, recent advances in the identification of EL 2, which is one of the most intensively studied point defects, are reviewed in conjunction with an antisite arsenic. The results, both experimental and theoretical, favor the models in which EL 2 is claimed to be originated from a complex or an arsenic-aggregate including antisite arsenic (s) . Such a defect is conceived as one of the defect structures of excess arsenics which are specific for compound semiconductors. [J. Cryst. Soc. Jpn. 28, 103 (1986) ] .
Compound semiconductor alloys have the flexibility to design energy band gap and/or lattice constant at desired value. This advantage has made these materials important for fabricating many advanced semiconductor devices, such as laser diodes and high-speed electronic devices. The growing importance in application has stimulated both theoretical and experimental studies on the fundamental properties of compound semiconductor alloys, such as bond, clustering, and immiscibility. This article reviews recent progress in understanding these fundamental properties of III-V compound semiconductor alloys.
Recent progess in techniques for growing semiconductor thin films is reviewed. Molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) have emerged as techniques for preparing ultrathin semiconductor layers with accuracies of atomic dimensions. New results using these techniques are presented. Intensity oscillations in reflection high energy electron diffraction (RHEED) can be used in MBE to monitor atomic-layer growth and recent reports show that MO CVD can produce monolayer superlattices. Finally, new techniques for growing semiconductor films such as MOMBE (metal-organic molecular beam epitaxy) and ALE (atomic layer epitaxy) are also presented. (J. Cryst. Soc. Jpn. 28, 124 (1986) ) .
Surface adsorbed or adsorbed layer of first material for the compound has rather stable mono-molecular structure, named as Langmuir-Blogett layer, which can react with the second material forming the monomolecular layer of the compound, with high accuracy. Moreover, photo-chemistry can include the chemical reactions with very high activation energy. However, in this case, most effective effect for the monomoecular thin crystal layer was the improvement of the crystal quality. With the measurement of the mass spectrometer, release of the methyl or ethyl were detected while the TMG or TEG was being absorbed and reacting with arsin. This means adsorbed species may be monomethyl or monomethyl gallium, and dimethyl or diethyl gallium, respectively, or might be both. In this paper, photo-assisted chemical reactions are explained and the molecular layer epitaxy, which made the crystal growth accurate in the order of single atomic dimentions, is explained, followed by the effect of ultra-violet light irradiations. These methods are also valuable to clarify the surface adsorption phenomena. Some experimental results are explained. (J. Cryst. Soc. Jpn. 28, 133 (1986) ) .
Super-doped structure (SDS) is reviewed. This is a very short period AlAs/GaAs superlattice in which the GaAs mid-layers are selectively doped with Si donor impurities, and is able to suppress the DX-center formation in n-type Al-Ga-As system. A new SDS concept and structural optimizations for replacing AlxGa1-xAs alloys and realizing high electron concentration are discussed. Superior electrical properties of SDS are shown in comparison with n-type AlxGa1-xAs (x>0.2) alloys. The applications of SDS to high speed devices and the prospects of other materials using this concept are presented. [J. Cryst. Soc. Jpn. 28, 142 (1986) ] .
Structures and defects of heterogeneous interfaces have been discussed using the concept of “coherency”which has been applied to interphase boundaries. Interfacial structures have been classified into three kinds, coherent, semicoherent and incoherent interfaces, depending on lattice mismatch. As a case study of the interface with great mismatch of about 10%, the structure of PtSi/ (111) Si interface has been discussed in detail on the basis of HRTEM images. The interface has been found to be atomically abrupt and has atomic steps which increases local coherency between PtSi and Si. (J. Cryst. Soc. Jpn. 28, 151 (1986) ) .
Several Methods recently developed for characterization of solid surfaces and solid-solid interfaces, mainly ion scattering techniques, are described. Channeling techniques utilizing high energy (-MeV) ions and channeling-blocking effects for medium energy (-0.1 MeV) ions have successfully been applied to structure analysis with small (-0.1-1Å) displacements of crystal atoms near surfaces and interfaces. Basic principles of those methods are explained, including computer simulations of particle trajectries. Low energy (-keV) ion scattering and scanning tunneling microscopy are shown to be fruitful techniques for surface characterization. A non-destructive method for interface analysis using energy dependent escape depths of keV electrons is also briefly mentioned. (J. Cryst. Soc. Jpn. 28, 160 (1986) ) .
The feature of magnetic bubble memory devices is nonvolatile and all solid-state. They are now used widely for NC machines, PUS terminals etc., because of their high-reliability and maintenance. free. Materials used for these devices are garnet single crystals. Recent research on high storage density devices is concentrated on ion-implanted bubble devices. These devices are based on the effect of magnetostriction that anisotropy field changes due to the internal stress in the ion-implanted layer of bubble garnets. This paper describes crystal structure and magnetic properties of bubble garnet films. Ion implantation effects in bubble garnets are also reported as a key-technology for ion-implanted bubble devices. [J. Cryst. Soc. Jpn. 28, 172 (1986) ] .
One often adds dopants to ceramics intentionally to control their properties. A new idea on the dopant effect is described through a study of La-doped barium titanate semiconductor. Recently many functional ceramics associated with grain boundaries, such as varistor, posistor and Mn-Zn ferrite with a very small eddy current loss have been developed. In this review essential character of grain boundaries in ZnO varistor is also described. Moreover reliability and reporducibility of properties of perovskitetype ceramics are discussed in relation to nonequilibrium structures appeared during the preparatian. [J. Cryst. Soc. Jpn. 28, 180 (1986) ] .
In anticipation of the continued size reduction of electron devices to the molecular level, new approaches to materials and techniques have been developed. The word‘Molecular Electronics’ has been created under these circumstances. Langmuir-Blodgett technique is one of the most promissing techniques to produce the molecular level electron devices. In this paper, LB materials and its application to microlithography as resists are discussed.