摘要:

A simple physical model that predicts charge accumulation at the dielectric interface of metal‐nitride‐oxide‐silicon (MNOS) structures is proposed and verified experimentally. The model is based on the presence of steady‐state current flow in the dielectric structure. Interface‐charge accumulation is shown to be determined by the requirement for continuity of current through the structure under steady‐state conditions. Continuity of current is established by accumulation of either positive or negative charge for a given polarity of charging voltage, depending on the relative current‐field characteristics of the silicon nitride and silicon dioxide layers. Due to the exponential nature of the current‐field characteristics, the time required to reach steady state is a strong function of the applied charging voltage. This leads to the observed charge storage property of MNOS devices. The hysteresis characteristic observed in MNOS structures is shown to be time‐dependent with a tendency to merge into a single‐valued dependence of accumulated charge on charging voltage as the steady‐state condition is approached. The validity of the theoretical model for both steady‐state and transient behavior is confirmed by current‐voltage, capacitance‐voltage, and turn‐on measurements of MNOS capacitors and transistors for different dielectric thickness ratios and over a wide temperature range. The underlying concept that charge accumulation establishes current continuity in a two‐layer dielectric structure should be valid, in general, for any two‐dielectric structure.

ISSN:0021-8979    

DOI:10.1063/1.1658181

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The room‐temperature Corbino magnetoresistance (&Dgr;R/R0)cof electron beam zone‐recrystallizedn‐type InSb films tends toward saturation in magnetic fields greater than 3 kOe. This fact as well as the presence of a large magnetoresistance (&Dgr;&rgr;/&rgr;0)Pobserved on long rectangular specimens (l/w>3) are interpreted in terms of a surface layer having a higher impurity concentration and lower electron mobility than the rest of the film. The experimental observations on zone‐recrystallized as well as dendritic InSb films is shown to be consistent with a model of two superposed layers, one with surface‐like and the other with bulk‐like electrical and galvanomagnetic properties.

ISSN:0021-8979    

DOI:10.1063/1.1658182

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Experiments are described in which a shock‐tube facility was used for the determination of the Hugoniot equation of state of granite. The facility was operated in two modes. Very low stress levels&sgr;[over equal to less-than]0.2 kbarswere obtained by allowing an air shock wave to impinge directly upon a sample material. Higher stresses,&sgr;[over equal to less-than]50 kbars, were obtained when the incident air shock wave was used to accelerate a metal projectile which then impacted upon the sample at a desired velocity. The instrumentation and data‐reduction methods are discussed and the resulting Hugoniot points for granite below and in the neighborhood of its dynamic elastic limit are given.

ISSN:0021-8979    

DOI:10.1063/1.1658183

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Room‐temperature tensile deformation experiments were performed on aluminum, magnesium, and molybdenum at 10−10Torr; at the same time, chamber pressure and residual gas species were monitored. Pressure increases noted during the deformations were attributed to specimen desorption resulting from imposed stresses and their concomitant lattice distortions. Hydrogen and methane were evolved from all three metals. The extent of desorption, however, was different for each material.

ISSN:0021-8979    

DOI:10.1063/1.1658184

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Direct measurements of the mean adsorption lifetimes and the activation energies of silver and gold have been made on a polycrystalline tungsten substrate. The lifetime was determined by the time constant of the exponential increase of the surface concentration when an atomic beam impinged on the substrate. The activation energy was determined by the slope of the logarithm of the lifetime as a function of the inverse substrate temperature. The adsorption lifetime of atoms on a metal surface is &tgr;=(1/&ngr;0) exp (E/kT), where &ngr;0is the vibrational frequency andEis the activation energy. The experiments were conducted in an ultrahigh‐vacuum system free of hydrocarbon contamination. A clean substrate surface was obtained by heating in a partial pressure of oxygen for a long period of time and flashing to 2500°K before each data point was taken. The well‐defined surface condition and the precisely known temperature allow reliable interpretation of the experimental results. The experimental results for silver and gold on clean, oxygenated, and carburized tungsten substrates when &tgr; is in seconds andEis in electron volts are the following: Ag on W, &tgr;=(1/3.6×1012) exp (2.9/kT); Ag on O&sngbnd;W, &tgr;=(1/1.43×1012) exp (2.06/kT); Ag on C&sngbnd;W, &tgr;=(1/8.2×1012) exp (3.18/kT); Au on W, &tgr;=(1/8.2×1013) exp (4.54/kT); Au on O&sngbnd;W, &tgr;=(1/4.7×1011) exp (1.99/kT); Au on C&sngbnd;W, &tgr;=(1/1.73×1014) exp (4.725/kT).

ISSN:0021-8979    

DOI:10.1063/1.1658185

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Measurements of the thermionic emission and electrical conductivity as a function of the temperature for fixed states of activation were obtained for each of the four barium chalcogenides. From the temperature dependences of these quantities the electron affinities were determined. The values obtained were 0.57 for BaO, 0.84 for BaS, 0.95 for BaSe, and 1.43 for BaTe. These values were found to be essentially independent of the state of activation of the samples.

ISSN:0021-8979    

DOI:10.1063/1.1658186

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

We have studied the growth of the silver sulfide tarnish film which forms on silver deposited on smooth, amorphous substrates and rough and smooth polycrystalline substrates. Both ellipsometric and electron‐microscope techniques were used to measure the average thickness of the tarnish films. The growth rate was found to be variable depending on the concentration of the sulfurous gases. In normal laboratory air (measured concentrations of H2S and SO2less than 0.2 parts per billion) a 1‐Å‐thick tarnish film can be expected to form in 1 h, 3–6 Å in 1 day, 15–30 Å in 1 week, and 60 Å or more in 1 month. The tarnish growth can be completely stopped by placing the silver in a dry‐nitrogen atmosphere. Conversely, in a humid atmosphere containing about 10% H2S, growth rates of as much as 100 Å/h can be obtained. The silver sulfide formed as small, randomly spaced, approximately round clumps having a site density about one hundred times larger than the patch density reported for thermally etched silver surfaces. All clumps nucleated on initial exposure, the clump density remained constant with time, and the clumps grew much slower than the tarnish patches on thermally etched silver. Coalescence toward a continuous film was slow; even after 41 days, only 53% of one silver surface was covered with tarnish.

ISSN:0021-8979    

DOI:10.1063/1.1658187

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The planar Hall effect has been described by theoretical analyses, and previous investigators have shown that the observed effect is consistent with these predictions. However, the amount of experimental data reported to date is small, and the work described herein provides additional data concerning the planar Hall effect in both polycrystalline and single‐crystal thin films. The calculations of the planar Hall coefficient and of the magnetoresistance factor based on these data show close agreement with the data obtained by other investigators. It is also apparent that, as has been predicted from theory, the influence of the crystalline symmetry is not dominant in the effect in ferromagnetic films at room temperature. The observations also indicate that the planar Hall effect may be potentially useful in electronic‐device applications.

ISSN:0021-8979    

DOI:10.1063/1.1658188

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The oriented overgrowth of titanium films obtained by evaporation in an ultrahigh‐vacuum system onto mica was studiedin situby reflection electron diffraction and, after withdrawal from the system, by transmission electron microscopy and diffraction. Films with a thickness of 100 Å or more, prepared on a mica at temperatures of 500°–600°C, are epitaxial single crystals of hexagonal structure; their basal plane is parallel to that of the substrate and the crystallographic axes within the contact planes form an average angle of 30°. These single‐crystal films have a smooth surface and are composed of subgrains rotated around thecaxis with respect to each other, forming angles up to 4°. Films thinner than 100 Å are only partially oriented. Coalescence in these films takes place at a very early stage of growth and continuous films of about 100 Å are obtained, in contrast with the growth of other metals on mica.

ISSN:0021-8979    

DOI:10.1063/1.1658189

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A new, well‐defined metal vapor device called the heat‐pipe oven has been developed on the basis of the heat pipe, a heat conductive element designed by Grover and his co‐workers in Los Alamos. It continuously generates homogeneous vapors of well‐defined temperature, pressure, and optical path length. The vapor is confined by inert gas boundaries which remove the window problem and allow a direct pressure measurement without relying on vapor pressure curves. Due to the continuous evaporation and condensation the vapor purifies itself during operation.

ISSN:0021-8979    

DOI:10.1063/1.1658190

出版商:AIP    

年代:1969

数据来源: AIP