摘要:

The diffusion of Se‐75 has been studied in crystals of PbS, PbSe, and PbTe annealed under argon at 700°C. The relative diffusivities wereD(PbS)≈D(PbSe)⪝D(PbTe). Adding bismuth to PbSe yields a higher diffusivity than in undoped crystals of PbSe while additions of silver do not change the diffusivity. At 700°C the diffusivity of selenium in PbSe was studied as a function of selenium partial pressure. For 10−4≤pSe2≤ 80 Torr,D∝pSe21/4while forpSe2> 80 Torr,D∝pSe21/2. ForpSe2< 10−4Torr, the diffusivity was not a function of selenium pressure.

ISSN:0021-8979    

DOI:10.1063/1.1659321

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A comparison is made between optical and scanning electron microscopy techniques on germanium surfaces that have been etched in several common chemical etchants. The morphology of the etch pits due to dislocations and different types of surface preparation are discussed. The high resolution and depth of field of the scanning electron microscope allowed resolution of the fine structure of the etch figures. Due to the manner in which the image is formed on the scanning electron microscope, the limit of resolution is much higher and light interference encountered using standard metallurgical microscopes is eliminated.

ISSN:0021-8979    

DOI:10.1063/1.1659322

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Ceramic samples of SrTiO3, containing a wide range of solid substitution of trivalent rare‐earth ions, have been fabricated and examined in detail. Well‐developed dielectric relaxation was observed in samples containing lanthanum, praesodymium, neodymium, samarium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium, butnotin samples containing cerium or europium. The relaxation occurs at normal low radio frequencies (102−105Hz) in the temperature range −150° to +40°C, and there is a systematic variation of the relaxation parameters with both concentration and ionic size of the substituted ion. X‐ray and density measurements confirm that as with lanthanum [T. Y. Tien and L. E. Cross, Jap. J. Appl. Phys.6, 459 (1967)]. and bismuth [G. I. Skanavi, I. A. M. Ksendzov, V. A. Trigubenko, and V. G. Prokhvatilov, Sov. Phys. JETP6, 250 (1959)] substitutions, two rare‐earth ions and an associated vacancy substitute for three strontium ions in the ``A'' sites of the perovskite lattice. Possible explanations for the dielectric behavior are considered and it is shown that the data are consistent with an ionic model proposed earlier by Skanavi. [G. I. Skanavi and E. N. Matveeva, Sov. Phys. JETP3, 905 (1957)].

ISSN:0021-8979    

DOI:10.1063/1.1659323

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Three‐terminal dielectric measurements of the weak‐field permittivity have been carried out on single crystals of bismuth titanate (Bi4Ti3O12), which contained only ``narrow‐angle'' twin walls. The pseudo‐orthorhombic &egr;a, &egr;b, &egr;cin these twinned monoclinic crystals show strong dispersion in the frequency range 100 Hz‐1 mHz, and only above 1 mHz are the data representative of the intrinsic properties. The dispersion is thought to arise from space charge developed through the high conduction current at elevated temperatures and not from domain wall motion or damped piezoelectric resonance.

ISSN:0021-8979    

DOI:10.1063/1.1659324

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Steady‐state high‐field electron conduction characteristics have been computed for a model in which the film contained electron traps with distributed binding energy and a compensating positive charge. Electron injection was taken to occur by the Schottky effect, trapping was considered as field independent, and detrapping as governed by the Poole‐Frenkel equation. The results illustrate various types of behavior according to the values of some of the model parameters.

ISSN:0021-8979    

DOI:10.1063/1.1659325

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

An analytical method has been developed for solving the partial differential equations that govern double‐stream diffusion under very general conditions. The diffusion coefficient of the slow stream is set equal to zero. The trapping and releasing rates and the diffusion coefficient of the fast stream are assumed to be functions of distance and time rather than constants. General solutions of the equations which satisfy the boundary and initial conditions for the two important cases of a thin planar source and a constant surface concentration are obtained in terms of the diffusivity of the fast streamD1(x). The expressions obtained for the trapping and releasing rates are found to be physically realizable. Expressions for the concentration of the diffusing substanceN(x, t) are obtained by considering suitable forms ofD1(x). By varying the parameters in the expressions for the functionN(x, t), concentration profiles are obtained which give a reasonable fit to the experimental data. A method is also developed to define the nominal Fick's diffusivity from the expressions of the apparent diffusivity. The values computed are of the same order‐of‐magnitude, but not in complete agreement, with those calculated using other methods.

ISSN:0021-8979    

DOI:10.1063/1.1659326

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The optimum conditions in operating a thermal diffusion column have been searched using argon gas. The results obtained were compared with the theoretical values. Two molecular models used for the comparison with the experimental results are the inverse power model and the Lennard‐Jones (12–6) potential model. The former showed a little better agreement with our results than the latter. WhenP4is plotted as abscissa andP2/lnqas ordinate, the relationP2/lnq= (1/a) (P4+b) gives a straight line using the assumption given by Furryet al. Substituting the experimental results in this equation, the time‐course variation of the values ``1/a'' and ``b/a'' from the slope and intercept of these linear plots was obtained. The variation ofaandbwith time is useful as a clue to see if the system is in equilibrium or not. Minimum values were observed near the optimum pressure in each operating time. Theoretical calculation of the relaxationtrwhich characterizes the approach to equilibrium was 1.04 h. Employment of direct current to heat the wire was a little better than the alternating current.

ISSN:0021-8979    

DOI:10.1063/1.1659327

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A model of enhanced diffusion of boron and phosphorus in silicon is proposed, which includes the effects of plastic deformation and the degeneracy of highly doped silicon. Numerical solutions of the diffusion equation with concentration‐dependent diffusion constant are presented, and the average conductivities of typical `anomalously diffused' silicon layers are given as a function of surface concentrations. Also discussed are the effects of background doping levels and surface concentrations on the effective diffusion constant and its measured activation energy.

ISSN:0021-8979    

DOI:10.1063/1.1659328

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The mode concept of a waveguide containing isotropic medium must be generalized when it is applied to waveguide containing gyromagnetic medium. For ferrite‐ or YIG‐rod waveguides, three families of surface waves are found to exist. They are named as dynamic, surface, and volume modes. Dynamic modes are forward waves. Both surface and volume modes become backward waves when their phase velocities are much smaller than the velocity of light, i.e., large &bgr; values. The transverse‐field vectors are generally elliptically polarized. Therefore, a stationary observer is not able to see the azimuthal and radial variations of a mode. Only by an observer rotating at radian frequency &ohgr;/ncan a constant transverse‐mode pattern be recognized. Using both amplitude and serrodyne‐phase measurements, the differences between the mode concepts of an isotropic rod and a gyromagnetic YIG‐rod waveguide are demonstrated. The same concepts are shown to be applicable to both the gaseous‐ and semiconductor‐plasma waveguides.

ISSN:0021-8979    

DOI:10.1063/1.1659329

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The intrinsic carrier concentration, reduced Fermi energy, electron effective mass, and the Fermi energy with and without doping are calculated for Hg1−xCdxTe withx>0.16 and 50<T<350°K. The calculations take into account the nonparabolicity of the bands by using thek·pmethod (Kane model) to determinenand by using the most recent linear temperature dependence of the bandgap. By fitting thenicurves calculated for nonparabolic bands to the expression for parabolic bands, the following approximation for the intrinsic carrier concentration was obtained:ni=(1.093−0.296x+0.000442T)5.16(1014)(Eg)3/4(T)3/2exp(−Eg/2kT).

ISSN:0021-8979    

DOI:10.1063/1.1659330

出版商:AIP    

年代:1970

数据来源: AIP