Showing papers in "Japanese Journal of Applied Physics in 1967"

Spectral Emissivity of Silicon

Abstract: The emissivity of silicon was observed in the spectral region from 0.4 to 15 µ at various temperatures from 340°K to 1070°K by using two n-type specimens with the resistivity of 15 ohm-cm and 7×10-3 ohm-cm at 300°K, respectively. The thermal radiation of silicon consists of three types due to band-to-band transition, free carriers and lattice vibration. It was made clear from the emissivity measurement that, in a pure specimen, the radiation due to lattice vibration is conspicuous at low temperatures, while that due to free carriers is predominant at higher temperatures, and that, in a doped specimen, the radiation due to free carriers is predominant even at low temperatures. The observed emissivity is close to the theoretical formula represented by the refractive index n and the extinction coefficient k. The temperature dependence of n and k is shown and a brief discussion is also added.

An Electron Microscope and Electron Diffraction Study of Fine Smoke Particles Prepared by Evaporation in Argon Gas at Low Pressures (II)

Abstract: This paper forms a continuation of the previous paper of almost the same title (Kimoto et al., Japan. J. appl. Phys. 2 (1963) 702). The materials examined include all the metals studied in the previous paper, Mg, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ag, Cd, Sn, Au, Pb and Bi plus the five elements, Be, Ga, Se, In and Te which have been newly added. One of the advances in the present study is the improved purity of the argon used. Thus, beautiful crystal habits have been observed for many of the elements. A small amount of oxygen, for example 0.03 mm Hg of oxygen in 6 mm Hg of argon, caused remarkable deterioration in the crystal habit of the particles. New modifications of crystal structure were found among the particles of chromium aud manganese. A few of the previous results are corrected because they were found to be due to impurities in the argon.

Infrared Lattice Reflection Spectra of II-VI Compounds

Abstract: The reflection spectra of cubic ZnS, ZnSe, ZnTe and CdTe, hexagonal CdS, CdSe and ZnS were measured in the spectral region from 20 µm up to about 100 µm. The Reststrahlen bands thus obtained were analysed using Drude dispersion relation and the following values of transverse optical mode frequency (νt) at the zone center were determined: cubic ZnS, 282 cm-1; ZnSe, 207 cm-1; ZnTe, 177 cm-1; hexagonal CdS, 234 cm-1 and 241 cm-1 for the vibrations parallel and perpendicular to the c axis respectively; hexagonal CdSe, 167 cm-1 for unpolarized radiation; hexagonal ZnS, 274 cm-1 for the vibrations of both polarizations. The longitudinal optical mode frequency at the zone center, the Szigeti effective charge and the other dispersion parameters were also obtained. νt was also obtained from the transmission spectrum of an evaporated thin film and was found to be in good agreement with the value obtained from the reflection analysis.

Piezoelectric and Elastic Properties of Lithium Niobate Single Crystals

Abstract: Piezoelectric and elastic constants of lithium niobate single crystal were measured in the temperature range between 20°C and 200°C. These constants were obtained by measuring the resonant and antiresonant frequencies of the length-extensional mode of bars with various orientations. The measured constants are all of the piezoelectric strain constants and the dielectric constants and a part of the elastic compliances, namely, sE11, 2sE13+sE44, sE14 and sE33. Values at 20°C and their temperature dependence are as follows. The constants d and s are expressed in units of 10-8 statcoulomb/dyn and 10-12 cm2/dyn, respectively: d15=222[1+(T(^°C)-20)2.8×10-4]; d22=62.3[1+(T-20)×2.4×10-4]; d31=-2.59[1+(T-20)11×10-4]; d33=48.7[1+(T-20)2.9×10-4]; s11E=0.564×[1+(T-20)1.5×10-4]; 2s13E+s44E=1.39[1+(T-20)2.0×10-4]; s14E= -0.084; s33E=0.494[1+(T-20)1.5×10-4]; e11T=84.6; e33T=28.6; k31=0.02; k22=0.32; k33=0.47. The electromechanical coupling factor k'31 of zyw-45°-cut bar amounts to 0.50.

Electrostriction in Perovskite-Type Ferroelectric Ceramics

Abstract: The electrostriction and polarization in the perovskite-type ferroelectric ceramics have been calculated in the state under the arbitrary biasing field. Domain configurations produced by 180°-reversal or 90°-rotation have been represented here by the threshold angle θ180 or θ90; that is, domains, making smaller angles than θ180 or θ90 after the switching once occurs, are completely reoriented under the given bias. The electrostriction and polarization can be calculated as functions of θ90 and θ180, from the spontaneous strain and polarization of the crystal. The spontaneous strain in the rhombohedral crystal has been found as (3/2)[(π/2)-α] for the first time. Bias dependence of θ90 and θ180 have been obtained from the experimental results on the basis of the present calculations. Some discrepancies between the results and the expectation based on the activation field considerations are presumably due to the mechanical stress accompanied with 90°-rotations, and to the interaction of 180°-reversals and 90°-rotations.

Structure des Oxides de Tantale

Abstract: The structure change of tantalum on heating in air and oxygen was followed by X-ray diffraction. Numerous forms of Ta oxides have been identified. Ta-(O) (solid solution), TaOy, TaOz, δ-form and β-Ta2O5 are formed in air at either atmospheric or reduced pressure. The nitrogen in the air is important for high temperature oxidation of tantalum since nitrides such as Ta2N and δ-TaN were observed. Heating of Ta powder in oxygen causes violent ignition and the α-form which has hitherto been considered to be a high-temperature form of Ta2O5 is obtained. The transformation α→β occurs on heating in oxygen and the inverse transformation β→α occurs on heating in vacuum at a temperature higher than 1300°C. The helium method of density measurement showed that the α-form is an oxide lower than Ta2O5. In the products of thermite reactions of (Ta+CuO) system, the dioxide TaO2 and a new cubic form of Ta oxide were observed.

Growth Ridges, Etched Hillocks, and Crystal Structure of Lithium Niobate

Abstract: Growth feature of a LiNbO3 crystal obtained by the pulling method has been studied. The formation of growth ridges was interpreted as the intermittent growth of the form {10}, which was the most readily grown form from the melt. The point group of the high temperature, paraelectric phase was uniquely determined as 2/m from the symmetry elements of the configuration of ridges. On (00) planes, the triangular etched hillocks were observed. Orientations of the hillocks on the antiparallel domains were related by 2-fold rotation axis parallel to [100] consistent with the phase transition of the type 2/m→3m. The atomic arrangement in the form {10} was examined, and a three-dimensional framework of the corner-shared Nb-O octahedra, similar to the one in perovskite, was found.

Metallurgical Investigations with a 500 kV Electron Microscope

Abstract: Metallurgical investigations such as recrystallization, martensitic transformation and dynamic behaviors of dislocations have been carried out with a 500 kV electron microscope. The critical foil thickness sufficient to observe the same dynamic behaviors of these phenomena as occurred in bulk specimens is about 1 µ for recrystallization in aluminum and iron alloys, and 3 µ for cell formation in aluminum. On the other hand, foil thickness which allows observation with the 500 kV electron microscope is practically above 8 µ for annealed aluminum and above 2 µ for annealed iron and copper, and it is about one half in order to allow continuous observation of the dynamic behaviors of phenomena. It is concluded that the 500 kV electron microscope has great advantages for the dynamic investigations of metals, especially of materials with the atomic number smaller than 15 such as aluminum and many of ionic crystals.

Dissociative Diffusion of Nickel in Silicon and Self-Diffusion of Silicon

Abstract: Behavior of electrically active nickel which acts as an acceptor in silicon is studied. Energy level of 0.41±0.01 eV below the conduction band at about 330°K, which includes the effect of the statistical weight factor, solubility of NS°=1026exp [-(3.1±0.2)/kT] cm-3 and reciprocal product of time constant of annealing of supersaturated state by dislocation density of 1/τnd=1.3×10-2exp [-(1.4±0.2)/kT] cm2 sec-1 have been obtained by Hall coefficient and resistivity measurements. It is concluded that the electrically active nickel atoms occupy the substitutional sites and nickel diffuses dissociatively and that the self-diffusion constant of silicon is 30exp [-(4.5±0.4)/kT] cm2 sec-1.

On the Phase Transformation of VO2

Abstract: Phase transformation of VO2 was studied by the optical microscopy, the X-ray difraction and the electrical resistance. Growth of transformed regions from sites of nucleation was observed in micrographs. The critical temperature of the transition and the rate of the growth were dependent on the mechanical strain. Apparent growth velocities were 0.01~1 mm./sec. at heating rates of 0.1~6°C/min. The intermediate phase suggested by Umeda et al with NMR was identified with a phase observed by our experiment. The lattice constants are a=5.80 AA, b=4.52 AA. c=5.38 AA, α=91.55°, β=122.78°, γ\doteqdot90°. Both the impurities of Al, Fe, and Cr and the reduction were effective for the creation of the triclinic phase. The low temperature phase which is normally monoclinic was found to be triclinic for those crystals which have the wider temperature range of the intermediate phase. The intermediate phase was explained assuming a metastable structure stabilized by the Magneli defect.

Preparation of Fine Metal Particles by Means of Evaporation in Xenon Gas

Abstract: Fine particles of Mg, Zn, Cd, Al, Fe, Cu and Ag were prepared by means of evaporation in helium gas Compared with those prepared in argon gas (Japan J appl Phys 2 (1963) 702), the particle size was much smaller, provided the pressure was the same To obtain the same size, the pressure of helium had to be about ten times as large as that of argon

Radiative Transition Probabilities in Tb3+ and Fluorescence Colors Producible by Tb3+-Activated Phosphors

Abstract: For the purpose of evaluating the electric dipole and the magnetic dipole transition prababilities in Tb3+, the reduced matrix elements for 5D4→7FJ and 5D3→7FJ have been calculated. From the results, fluorescence colors producible by Tb3+-activated phosphors have been predicted: The best green colors with short persistence have the chromaticity coordinates around x=0.321, and y=0.651. For this purpose, Tb3+ ions should be embedded in lattice sites without inversion symmetry. The nonradiative transition probabilities for 5D3→5D4 due to multipolar interactions have been evaluated. When the Tb concentration is higher than several per cent, the quadrupole-dipole interaction between the Tb3+ ions in the metastable state 5D3 and those in the ground state 7F6 is predominantly responsible for the nonradiative 5D3→5D4 relaxation.

X-Ray Study on the Phase Transition of NaNO2

Abstract: The precise temperature dependence of x-ray diffraction effects near the transition temperature of ferroelectric NaNO2 crystal has been examined The satellite reflections, 1±σ 5 0, start to appear at Ts, 02°C below the well-known first-order transition point Tt Marked asymmetry of the satellite reflections was sometimes observed when a multi-domain crystal was measured The period of the sinusoidal modulation along the a-axis varies from 103 a0 to 84 a0 with increasing temperature The effect of a d c external field along the b-axis on the x-ray diffraction effect was also examined The experimental evidence indicates the presence of a new phase between Ts and Tt Some thermodynamical calculations for the phase transition of NaNO2 were carried out To explain the intensity asymmetry of the satellite reflections the diffraction effect for a distorted crystal was also calculated

Effect of Stress on Germanium and Silicon p-n Junctions

Abstract: The current change induced by uniaxial compression is calculated for the , , and orientations. The change in minority carrier mobility is considered to higher order for stress in addition to the change in minority carrier concentration. The differences of heavy hole mass and light hole mass and their stress dependence are taken. Experimentally obtained deformation potential constants are used. The minority carrier concentration decreases at low stress level and then increases rapidly with increasing stress. The orientation which shows the maximum current change corresponds to the direction of the rotating axis of conduction valley. The orientation dependence of the current change is in good agreement with that obtained experimentally for the uniaxial and anisotropic stress effects. In Ge, the apparent stress coefficient of band gap is obtained as -10.5×10-12 eV cm2/dyn for the orientation.

Holographic Generation of Contour Map of Diffusely Reflecting Surface by Using Immersion Method

Abstract: This paper describes the double exposure holographic formation of a contour map over a diffusely reflecting or transmitting of arbitrary shape and surface finish by using an immersion method with media of different indices of refraction between successive exposure. A wavelength λ effectively contributing to the fringe contour is given by λ0/Δn where λ0 is the wavelength of the laser and Δn is the index variation. Index variations were introduced by pressure difference in Freon to give λ=600 µ and 200 µ, and by the combination of two liquids to give 14 µ and 25 µ, thus extending the change of height corresponding to each fringe contour continuously up to one thousand times greater than with the optical Fizeau fringes. A correcting plate of a Schmidt camera in the grinding process was used as a test object and its figuring error were analyzed.

Hall Effect and Thermoelectric Power in Semiconductive TiO2

Abstract: The electrical properties of the conductive TiO2 (rutile) ceramics, as well as single crystals, doped with Nb2O5 or Ta2O5 were investigated by Hall effect and thermoelectric power measurements. These properties were shown to be strongly dependent on the doping concentration which covered the range up to 4 mole-percent. The experimental results indicate that the specimens are non-degenerated n-type semiconductor with a density-of-states effective mass of m*=20 m. At room temperature, where lattice scattering plays a dominant role, Hall mobility is about 0.4 cm2/Vs. for lower doping level and it falls down to 10-2 cm2/Vs. with the increasing doping concentration. The mobility increases in the slightly doped specimens at liquid nitrogen point, while it decreases in the specimens doped more heavily than 0.1 mole-percent. The activation energy of the donor centers due to the doping is 0.02 eV. The reduced specimen not intentionally doped, shows a shallower level nearly equal to 0.01 eV.

Dielectric Relaxation in Strontium Titanate Solid Solutions Containing Lanthania

Abstract: The dielectric properties of solid solutions in the system SrTiO3-La2/3TiO3 were measured in a frequency range from 200 to 105 Hz and at temperatures from -190 to 400°C. The relative permittivity of the solid solutions is lower that of pure SrTiO3 and pronounced dielectric nonlinearity was not observed. Two separate groups of dielectric relaxation peaks were observed, a low temperature relaxation which occured in a temperature region below room temperature and a higher temperature process which occured at about 200°C. The experimental results were analyzed in the light of current theories for relaxation in high permittivity materials. It is suggested that the higher temperature relaxation is associated with a Maxwell-Wagner phenomenon due to the different properties of grain and grain boundaries in the ceramic specimen. For the lower temperature process the evidence is compatible with an ionic model of the Debye type. It is suggested that the existence of the A site vacancy in the perovskite ABO3 lattice introduced by the lanthanum substitution distorts the oxygen octahedron, producing more than one possible "non central" sites for the Ti4+ ion. The relaxation arises from the thermal motion over potential barriers separating these alternative sites.

222 Electron Reflection from Aluminium and Systematic Interaction

Abstract: Energy dependence of electron diffraction from a bent wedge crystal of Al was investigated experimentally at energies from 100 KeV to 1 MeV as well as theoretically with particular interest in the systematic interaction. The (222) intensity at the crystal orientation for this reflection is remarkably reduced under observation at some 600 KeV where two dispersion sheets cross each other; furthermore the measured energy-dependence of a fine fringe appearing in the extinction contours agrees fairly well with our theoretical prediction. Around the orientation for (111) reflection the observed profile of (222) image-intensity includes a fringe synchronous to that in the (111) intensity, correspondingly to Vingsbo's observation for an MgO crystal (Proc. 6th International Congress for Electron Microscopy, Kyoto (1966), Vol. I 109.). As for (111) extinction distance, the present theoretical estimation gives a fringe-period shorter by 9% and 16% at 100 KeV and 1 MeV respectively than the simple two-ray approximation does.

Stress in Vacuum Deposited Films of Silver

Abstract: Measurements have been made of the tensile stress in silver films evaporated in a vacuum of 1–2×10-5 torr on to mica strips, electron microscopic observations of the film structure being carried out on the other hand. Films having various thicknesses ranging from about 30 A to 1000 A were under investigation. The tension per unit width of the film, S, increases sigmoidally with the film thickness d: In the initial stages of film growth in which the film is composed of isolated islands, S is very small; S increases rapidly during the late coalescence stage and the channel stage; after the completion of a continuous, hole-free film, S does increase with d, but at a much slower rate. The mean stress per unit cross section of the film, σ (=S/d), increases sharply with d to assume a maximum at a thickness around 200 A where the "shoulder of the S-d curve is located, and decreases gradually as d increases further.

The Observation of Thick Specimens by High Voltage Electron Microscopy. Experiment with Molybdenite Films at 50-500 kV

Abstract: This study was designed to investigate how much the maximum thickness of crystalline specimens which was adequate for transmission observation could be increased with the accelerating voltage. Molybdenite films of 0.5–7.0 microns thickness were used for specimens. Dislocations in films of about 0.5, 1, 2 and 3 microns were found to be observable under routine irradiating conditions at 50, 100, 200 and 500 kV, respectively. With focused irradiation the thicknesses were about 30% larger, although the image quality was low. Dislocation images were generally obtained when the effect of the so-called anomalous transmission, which disappears for very thick specimens, was apparent in the corresponding diffraction pattern. The theoretical background for images of thick specimens is discussed. Reference is also made to preliminary results obtained with silicon. No conclusion has been drawn on the voltage dependence of the maximum thickness of specimens adequate for transmission observation.

Traveling-Wave Amplification by Drifting Carriers in Semiconductors

Abstract: The interaction of drifting carriers in semiconductors with traveling waves in an external slow-wave circuit is investigated. The electromagnetic fields are obtained in the circuit-space and in the semiconductor-space by three-dimensional analysis. A dispersion relation for this system is derived by connecting admittances in both spaces at the semiconductor surface. Characteristics of propagating waves are similar to those of ultrasonic wave amplification. Attenuation turns into gain when the drift velocity of the carriers exceeds the phase velocity of the wave. For illustrative examples, n-type InSb at 77°K and GaAs at room temperature are examined. Attainable gains are expected to be about 200 dB/mm for both materials.

The Formation Mechanism of Domain Etch Patterns in Triglycine Sulfate Crystals

Abstract: Conditions necessary for obtaining domain patterns in triglycine sulfate-water system were studied. Effects of surface charge, stirring, undersaturation and composition of etchants were examined by rub technique, jet technique and observation of etched crystal surfaces. Surface charge was necessary for revealing domains. Domain patterns were revealed at low undersaturations, while at high undersaturations dislocation pits. It was found that the positive glycinium ions play a major role in domain pattern detection while the negative sulfate ions a minor one. Domain pattern formation by etching in triglycine sulfate is probably due to the difference in the rate of diffusion of the glycinium ions into the solution between at the positive and at the negative ends of the dipole. The relation between the conditions required for revealing domains and those for revealing dislocation pits is discussed on the basis of current theories of crystal dissolution.

Studies on Pb(Zr-Ti)O 3 Ceramics with Addition of Cr 2 O 3

Abstract: The solubility limit of Cr2O3 into Pb(Zr-Ti)O3 was determined as about 2.2 mole % of ½Cr2O3. In a region out of the limit, three phases were found; the perovskite-type solid solution, the baddeleyite-type ZrO2 and 2PbOCrO3. By additions of Cr2O3 within the limit, the tetragonality or the difference of rhombohedral angle from π/2 is decreased, and the Curie point is lowered. The temperature, bias and aging characteristics of the piezoelectric ceramics with Cr additives were measured. The temperature coefficient of frequency constant decreases with Cr concentration. The addition of Cr2O3 decreases the dielectric and elastic anisotropies, and increases the coercive field. The remanent electrostriction if notably large compared with that in the plain Pb(Zr-Ti)O3 ceramics. The back-rotation of 90°-rotated domains with time tends to play a significant role in the ceramics with Cr additives, and this is considered as one of the reasons for the improved time stability in this system.

Phase Relation and Kinetics of the Transformations in Au-Cu-Zn Ternary Alloys

Abstract: The phase relation in the β phase AuxCu55-xZn45 ternary alloys was studied There appear two types of ordered phases, ie, the Heusler-type and the CsCl-type superlattices, and a martensite structure at low temperatures The critical temperature (Tc) of CsCl-type superlattice becomes higher than that (455°C) of the Cu-Zn binary alloy with the increase in Au content Tc of the Heusler-type has a maximum (390°C) near the stoichiometric composition of AuCuZn2 The martensitic transformation temperature (T0) increases up to a maximum (45°C) at the 26 at% Au and then decreases with the further increase in Au content The nature of the stability of the β phase was discussed from the view point of ionic radii of the constituent elements, electron atom ratio and quenched-in vacancies