Recent investigations of chalcogenide amorphous semiconductors by ESR of doped Mn are reviewed. Such a technique is found to be useful for investigating the impurity effect and the structural change due to annealing and photo-irradiation. First, detailed studies on ESR spectrum of Mn in various chalcogenide semiconductors are described and shows that the ESR spectrum is sensitive to the amorphous structure. Second, we show that the ESR measurement together with optical and electrical measurements reveal the effect of doped Mn from the microscopic point of view. Finally, the structural change due to annealing and photo-irradiation which is characteristic of lone-pair amorphous semiconductors (amorphous semiconductors with lone-pair electrons) is described and the ESR study is shown to be useful to clarify microscopically the structural change.
Information concerning point defects in silicon and germanium have been compiled. Tables for vacancy-type and interstitial-type defects in silicon are prepared to show the fundamental properties of these defects. On the other hand, the present state of knowledge of point defects in germanium is meagre, allowing only qualitative argument. The various ionization effects which have aroused intriguing interest, make the defect problems in semiconductors very complex. A brief survey of this topics has been made. There seem to be various discrepancies between our knowledge of defects produced by irradiation at low temperature and of those in thermal equilibrium at high temperature. The knowledge of the latter is important because it provides bases for considering diffusion, heat treatment and quenching. A unified theory presented so far has been examined especially with regard to its basis. Self diffusion mechanisms and the interpretation of swirl-defect characteristics are discussed.
Measurement of low humidities (_??_33% RH) is done by a bimetallic psychrometer of temperature-difference type of which the wet bulb is wetted by a saturated water solution of magnesium chloride in place of pure water. The bimetallic psychrometer used in this study is composed of a compound bimetallic differential thermometer and a bimetallic thermometer. The wet part of the differential ther-mometer is wrapped with a gauze to which the saturated water solution of magnesium chloride is supplied at the time of measurement. Air of low humidities is obtained by bubbling through two baths of a saturated water solution of magnesium chloride. The necessary minimum ventilating velocity for the bimetallic psychrometer is found to be about 0.7m/s, the same as the case when the wet bulb is wetted with pure water. The results of the experiments show that the above mentioned measuring method is appli-cable to the low humidity range, with fairly good accuracy.
A new method for investigating an ion sheath is described. The elastic surface waves which propagate along the free surface of a piezoelectric crystal such as LiNbO3 are affected by the electro-magnetic properties of the medium adjoined to the surface. When the piezo-electric crystal is adjoined to a plasma, an ion sheath is formed between the plasma and the crystal. The interaction between an external field of the elastic surface wave, and ions in the sheath and electrons in a plasma causes attenuation of the wave amplitude and a change in the phase velocity. The theory and experimental method for the determination of the ion density in the ion sheath, the ion collision frequency and the sheath width from the attenuation of the elastic surface wave are reported. The results obtained in this paper are as follows; (1) the ion density in the ion sheath is 1. 79 times as large as the ion density in a plasma, (2) the ion collision frequency is about 57.3 MHz in the case of Ar gas plasma in which the degree of ionization is low, (3) the ion sheath width is 0.5_??_0.75 times the Debye length.
Transparent conducting films of tin oxide are prepared by thermal decomposition of a tin salt of an organic acid as a starting material. In order to investigate the doping effect, transparent conducting films of tin oxide containing antimony are prepared by thermal decomposition of the starting material mixed with a mixture made from tartaric acid and antimony oxide. These films were prepared on the microslide glass at the temperature range from 300°C to about 600°C in air, and the physical and electrical properties of the films were investigated. From the study of thermal decomposition of the starting material, it was found that the various gases produced by the thermal decomposition were harmless. The results of the structure analyses using X-ray diffraction pattern and electron micro-graph show that the films are polycrystals of tin oxide. Furthermore, the antimony in the tin oxide films doped with antimony was detected by an X-ray microanalyzer. The experimental results of transmission and electrical properties of the films indicated that the effect of this doping material was very remakable. This method, as compared with previous methods, is very convenient and simple for obtaining transparent conducting films with a comparatively low specific resistivity.
The fundamental factors which determine the characteristics of a (n+-p-n+)-n+ device are the applied voltage and illuminated light (L). Besides these factors, the characteristics of the device are influenced by external factors such as capacitance, resistance and auxiliary voltage. When a capacitance C is added between the main and auxiliary electrodes, , decrease of the frequency and the threshold voltage of oscillation, and increase of the output pulse current occur. The frequency ƒ is expressed as ƒ=a•C-k•Ln and the pulse width τ as τ=b•C+τ0. Connection of a resistance R increases the frequency. When an R-C parallel circuit is added, the minimum frequency ƒmin is determined by the value of C, and the frequency increases up to 50_??_60 times of ƒmin with decrease of R. Addition of an auxiliary voltage V1 decreases the threshold voltage of oscillation and increases the frequency.
A Fabry-Perot interferometer with free spectral range of 20 cm-1 is described, which can be assembled as tandem or multipass type using two different etalons; etalon A (R=82%) and etalon B (R=96%). The measured contrast of the tandem type is 4×104, and that of the triple-pass of etalon B is 109. The Brillouin spectra of diamond and the rotational Raman spectra of N2O gas are observed to test the performance of these etalon assemblies.