摘要:

It is known that dislocations in semiconductors can act as acceptors. This effect has been explained by noting that dislocations with edge components can have unpaired electrons at the terminating half‐plane which act as acceptors; thus a dislocation contains a line of uniformly spaced acceptors only a few angstroms apart. Inn‐type materials the dislocation line becomes negatively charged and a positive space charge develops around the line. The occupation statistics are strongly modified by the electrostatic energies involved. Certain approximate solutions to this problem have already been given by W. T. Read. This paper derives improved statistics which, in addition, explicitly take into account interactions between nearest‐neighbor electrons; the results are valid over the complete range of occupation. The statistics are given in terms of two functions which occur in the form of infinite series; the series have been evaluated over a considerable range of occupation and are herein tabulated. Techniques for use of the results are presented. Our theory was applied to a specific problem originally chosen by Read. The results fall between his most accurate approximations for this problem. Statistics have also been derived which take into account the proper spin degeneracy of acceptor states.

ISSN:0021-8979    

DOI:10.1063/1.1735883

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

An ion‐bombardment etching method was used to prepare synthetic fiber samples for study in the electron microscope. Reproductible results were obtained by bombardment in a constantly changing argon atmosphere at a pressure of 1–2 cm Hg for 2–5 min. The etch patterns produced by this method were characteristic of the orientation of the fiber samples which were investigated.

ISSN:0021-8979    

DOI:10.1063/1.1735884

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A new magneto‐oscillatory effect has been observed in the electron‐hole plasma within a semiconductor. The plasma can be produced by such agents as contact injection and optical or thermal excitation of minority carriers. When the semiconductor specimen is subjected to an electric field (through suitable contacts) and a magnetic field, current oscillations can be detected across a series load resistance. This device has been termed the oscillistor to suggest a semiconductor oscillator. The experiments suggest that the oscillistor mechanism involves a magnetically induced interaction of the bulk plasma of electrons and holes with the exposed free surface areas of the specimen.

ISSN:0021-8979    

DOI:10.1063/1.1735885

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Vand's analysis of distributions in activation energy is reexamined through a new derivation which leads to a better approximation to the activation energy spectrum and which permits a treatment of step annealing data. The cases of distributions in frequency factor and the twofold distributions in activation energy and frequency factor are also treated.

ISSN:0021-8979    

DOI:10.1063/1.1735886

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The six adiabatic elastic stiffness constants of bismuth have been determined at 301°K by an ultrasonic pulse echo technique. The results are:c11= 63.5,c33= 38.1,c44= 11.30,c66= 19.4,c14= +7.23, andc13= 24.5, all in units of 1010d/cm2. These values were redundantly determined by the measurement of 14 different velocities in four different single crystals of zone‐purified bismuth. The velocities are believed accurate to better than 1%, the principal error arising from the uncertainty of the transducer transit time correction. The moduli are in poor agreement with the previously determined static elastic compliance constants reported by Bridgman. Some data on the velocity of sound in bismuth at 98° and at 4.2°K are also presented.

ISSN:0021-8979    

DOI:10.1063/1.1735888

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Dislocation rosette patterns produced by spherical and pyramidal indentors on the cleaved surfaces of magnesium oxide crystals were studied in detail. The three‐dimensional arrangement of dislocation loops as deduced from the two‐dimensional etching patterns is discussed. Cracks formed on {110}90planes around pyramidal indentations are believed to be due to the interaction of dislocations on {110}45planes. The temperature dependence of hardness was found to be related to the widening of dislocation bands, rather than to the distance of travel of leading dislocations. Some observations were also made on the pinning of dislocations and recovery at elevated temperatures, and on the interaction of dislocations with grown‐in subboundaries.

ISSN:0021-8979    

DOI:10.1063/1.1735889

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The velocity of the sidewise 180° domain‐wall motion in single‐crystal BaTiO3has been measured over a temperature range from 25° to 100°C as a function of the applied electric field. The velocity, described byv=v∞exp(−&dgr;/E), where &dgr; is the activation field,Ethe applied electric field, andv∞the extrapolated wall velocity forE= ∞, increases by about four orders of magnitude with this increase in temperature. It was found that the temperature dependence ofvlies primarily in &dgr; and not inv∞. The magnitude of &dgr; decreases with increasing temperature and is also dependent on the impurity concentration in the crystal as well as the crystal thickness. The effects of impurities are most pronounced at room temperature, where (1/&dgr;) (d&dgr;/dT) is 1% °C−1for undoped samples and 2% °C−1for Fe doped samples. Though &dgr; itself is very sensitive to the sample thickness, (1/&dgr;) (d&dgr;/dT) does not appear to depend on the crystal thickness. Additional data are required before a critical comparison can be made between experiment and theory.

ISSN:0021-8979    

DOI:10.1063/1.1735890

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Instead of analyzing a portion of an hydromagnetic pinch apparatus in detail, and replacing the remainder by a boundary condition, the entire pinch apparatus is treated here as a single dynamical system. A circuit equation and a mechanical equation, coupled together, result. These equations describe the dynamical development of the pinch and exhibit explicity its dependence on the physical parameters (electrical and mechanical) of the system. As examples, the equations have been used to analyze the snow‐plow model and the adiabatic pinch, yielding curves that show the geometrical development of the pinch in time, as well as the distribution of mechanical and magnetic energies at any stage. Analogous analyses may be made for other physical quantities of interest, and can be used to adjust the parameters of the system so as to optimize specific pinch characteristics.

ISSN:0021-8979    

DOI:10.1063/1.1735891

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The eigenvalues of thegtensor of an irradiation produced defect of the quartz structure have been found to beg1= 2.0003,g2= 2.0006,g3= 2.0018. The data on the center are consistent with the assignment ofS= ½. Assuming that the hyperfine interaction with Si29(I= ½ and 4.7% abundant) is negligible, the envelope of the line is calculated for 4 widths of the line. Good agreement is found between the calculated envelope for a width of 0.2 oe and the envelope observed in &ggr;‐ray and in neutron‐irradiated (≤1018fast neutrons/cm2) silica. The observed envelope deviates from the calculated envelope for increasing neutron irradiation. It is suggested that a correlation of the Si‐O tetrahedra, similar to &agr;‐quartz, exists around any point in the more common forms of silicas and has a diameter of ≥5 A.

ISSN:0021-8979    

DOI:10.1063/1.1735892

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The dark current and photocurrent characteristics of amorphous selenium and arsenic‐selenium alloy films have been investigated. One millisecond after the application of an electric field, the dark current (neglecting capacitance charging) is several orders of magnitude higher than the steady‐state dark current. A hysteresis effect is observed in the dark volt‐ampere curves with the descending voltage branch exhibiting an exponential volt‐ampere relationship. The voltage of a charged Se plate in the dark discharges logarithmically with time as anticipated from the exponential volt‐ampere relationship. Upon admitting air to a freshly evaporated Se plate, a negative surface potential of 150 mv is observed. The phenomenon of ``fatigue'' (i.e., the temporary increase in dark current following an exposure to illumination) obtained with highly absorbed radiation indicates surface barrier effects exert a large measure of control over dark currents. Photogenerated holes and electrons in Se films are trapped with trapping parameters such that the hole range/unit field is on the order of 10−8cm2/v, and the electron range is less than 10−9cm3/v. The addition of As to the Se greatly increases the electron effective lifetime. Trapped holes are eliminated in the dark exponentially with time through a process having an activation energy of 0.77 ev. A 40‐mv negative surface photovoltage is observed in Se films upon illumination. This voltage may be accounted for by hole diffusion away from the surface. The addition of As to Se extends the spectral response into the red end of the spectrum, results in the initiation of secondary photocurrent effects, intensifies fatigue effects, and increases the softening temperature of the film.

ISSN:0021-8979    

DOI:10.1063/1.1735893

出版商:AIP    

年代:1960

数据来源: AIP