Electronic avalanche phenomena in semiconductors are described mainly in the view of ionization coefficient. The electric field dependence of the ionization coefficient in most of semiconductors can be surprisingly well fitted with Baraff's theory which has unified the lucky-electron model of Shockley and the diffusion approximation of Wolff. Electronic ava-lanche was so far an undesirable effect which deteriorates the junction characteristics, such as breakdown voltage and junction noise. But now, the avalanche phenomena are positively utilized to develop IMPATT diodes and avalanche photodiodes. In the high field domain of bulk effect devices, impact ionization also presents many interesting problems. To improve properties of IMPATT diode and bulk effect devices, more elaborate understanding of the avalanche phenomena is required.
Glazed palladium-silver thick-film resistors have been prepared by firing glazed palladium-silver paste screened on an alumina substrate, by varying the conditions of preparation. Such chosen conditions were temperature rise and fall rates, firing temperature and firing period. The electrical properties and stability of these specimens have been tested; electrical proper-ties measured were film resistance, temperature coefficient of resistor, and noise ; stability judged from life test, thermal shock and humidity test. From these tests it was found that electrical properties and stability of these resistors were affected in much the same by way firing tem-perature and period. They were influenced the most by temperature rise rate, but little by temperature fall rate.
Electrical properties of silicon oxide films prepared by glow discharge reaction between organic silicate and oxygen gas are reported. Properties of silicon oxide films are remarkably influenced by the reaction temperature. Silicon oxide films prepared by this process at a temperature below 200°C contain -OH and Si-OH groups from the observation of infrared absorption spectra. They have a larger dielectric constant than that of thermally grown oxide. The higher the reaction temperature is, the closer the properties of silicon oxide films are to those of thermally grown oxide. In the silicon oxide films prepared at the temperature of 300°C, the breakdown field is in the range of 5_??_10×106V/cm and the dielectric constant is 3. 6. MOM capacitor constructed by this process has a constant quality factor of about few thousand and capacitance independent of frequency up to about 10MHz.
Under such a condition that a bundle of non-parallel rays is incident upon the grating, the aberration of the Czerny-Turner mounting is studied for rays lying in the meridional plane common to optical elements of the spectrometer. The aberration is derived from the optical path function calculated up to the term of the fourth-order in grating width. The optical path function for the whole system is obtained by an addition of two functions of the same form, each corresponding to a half of the system. The function can be employed for analysis of problems under various conditions of mountings of spectrometers. As an example, the coma aberration may be eliminated, and the optimum width of the grating and the optimum positions of the slits which give the minimum deviation of focus with the wavelength scanning are determined. The aberration formula derived in the present work is applicable to the Monk-Gillieson mounting.
Photocurrent of vitreous semiconductors in the system Si-As-Te was found to be propor-tional to the square of the illumination intensity at lower intensities and linearly proportional at higher intensities: The superlinearity in the lower intensity region is different from results previously reported for other semicon-ducting chalcogenide glasses. A suggestion on the basis of the band model of amorphous solids is given for the relation between the superlinearity in photoconductivity and switching phenomena.