摘要:

Aukerman and Willardson's analysis of the temperature dependence of the two‐band Hall coefficient is extended to higher carrier concentrations, where the statistics are no longer classical. It is shown that the Hall coefficient behavior evolves in a characteristic fashion, and that useful information may be extracted from this behavior. Experimental Hall data onn‐type GaAs and GaSb and onp‐type GeTe, SnTe, PbTe, and Bi2Te3are found to conform to the predictions of the theory. The importance of distinguishing carefully between the effects of temperature and carrier concentration is emphasized, and it is shown that confusing the two can and has led to erroneous interpretations of experimental data.

ISSN:0021-8979    

DOI:10.1063/1.1714505

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A study has been made of the radiation‐induced conductivity (RIC) in poly[ethyleneterephthalate] (Mylar) films, using pulses of electrons of energies up to 30 MeV from a linear accelerator. The absence of polarization indicates that electronic conduction is responsible for the RIC, which has typical values of ∼10−8&OHgr;−1cm−1at 5×109rad(Mylar)sec−1. The RIC is a bulk effect and shows both a ``prompt'' portion which falls very rapidly at the end of an electron pulse and a ``delayed'' portion which persists for milliseconds. The prompt portion varies as the 0.8 power of the dose rate and is independent of pulse width. The delayed portion varies as a lower power, saturating at dose rates of ∼1010rad(Mylar)sec−1. The decay of the delayed portion is hyperbolic, and its rate is independent of temperature. The RIC increases monotonically with temperature in the range 100°–300°K. This behavior corresponds to a model in which one sign of carrier is rapidly and permanently trapped, the delayed conductivity being due to the other sign of carrier remaining free until it recombines. The saturation of the delayed conductivity is ascribed to a finite number of such traps.

ISSN:0021-8979    

DOI:10.1063/1.1714506

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The activation energy and the activation volume for diffusion‐controlled high‐temperature creep were measured by the change‐of‐slope method. The values obtained were: 9.7±0.4 kcal/g‐atom (or 0.42 eV) and 25.2±0.5 cc/g‐atom (0.55 atomic volumes); this value of the activation volume is at 1 kbar. From this the value at atmospheric pressure can be estimated to be 26.0 cc/g‐atom. It can be assumed that the activation energy and activation volume for self‐diffusion are given closely by these creep values inasmuch as the strain rates used were small (&egr;˙∼10−7sec−1) and the temperatures were relatively high (T∼0.9TM).

ISSN:0021-8979    

DOI:10.1063/1.1714507

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The room‐temperature reststrahlen spectra of flame fusion grown NiO and CoO, as well as those of three intermediate members of this solid solution series, are presented. A full Kramers‐Kronig analysis on all members has been performed and checked with damped oscillator calculations. The resulting refractive indices, extinction coefficients, dielectric constants, effective ionic charges (Szigetiq*), and characteristic frequencies are presented along with the lattice constants and are discussed in the light of their interrelation.

ISSN:0021-8979    

DOI:10.1063/1.1714508

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

High‐resolution, room‐temperature, infrared absorption measurements of boron‐ and lithium‐compensated silicon are reported. Isotopic shifts of the observed absorption bands with changes in lithium and boron isotopes are given. The absorption strengths of the bands at 681, 655, 584, 564, and 522 cm−1associated with lithium‐boron pairs, are all proportional to the impurity concentration from ∼2×1018to 1020cm−3. Weak bands associated with unpaired boron are also observed in the same samples at 644 and 620 cm−1. The 522 cm−1band shifts to 534 cm−1with change in lithium isotope and is nearly independent of the boron isotope. The frequencies of the remaining bands depend almost completely on the boron isotope.

ISSN:0021-8979    

DOI:10.1063/1.1714509

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A two‐band spherical model is used to represent the conduction electrons of the nonmagnetic transition metals with an incompletedshell. It is shown by comparison with experimental results that phonon‐induced interbands‐dtransitions are the major contributor to the electrical and thermal resistivities &rgr; andWat all but the lowest temperatures. Consequently, the momentum gap between thesanddbands is an important parameter of the theory and may be used to classify the behavior of &rgr; andW. At the lowest temperatures it is found that the experimental data for &rgr; of all the transition metals studied may be consistently interpreted if it is assumed that electron‐electron scattering processes are important.

ISSN:0021-8979    

DOI:10.1063/1.1714510

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The cleavage energies of single crystals of NaCl and MgO were measured in vacuum and in liquid nitrogen. The average value of the cleavage energy of NaCl while submerged in liquid nitrogen was 317 erg/cm2as opposed to 283 erg/cm2in vacuum at 77°K. The cleavage energy of MgO is 1300 erg/cm2, which agrees with values obtained at 300°K in air and in liquid nitrogen. This lack of atmospheric influence may be due to the inability of contaminants to diffuse into the crack tip of the specimen.

ISSN:0021-8979    

DOI:10.1063/1.1714511

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A technique was developed for the preparation of high‐quality single crystals of Mg2Ge with controlled dopings. It utilizes the reaction of stoichiometric amounts of the constituents in a graphite crucible inside a hermetically sealed tantalum bomb, followed by the solidification of the molten compound into a single crystal by lowering the bomb through a temperature gradient (Bridgman technique). Several crystals without intentionally added dopants were grown as well as crystals to which the donors antimony, arsenic, boron, the acceptor sodium, or the apparently insoluble element uranium, had been added.A technique was also developed for the preparation ofp‐njunctions onn‐type Mg2Ge, utilizing the alloying to and diffusing into the Mg2Ge of a thin evaporated gold film.p‐njunctions prepared in this way exhibit undesirably large reverse currents, but high breakdown field strength and very pronounced surface passivation properties, which might make Mg2Ge a desirable material for MOS (metal‐oxide‐semiconductor) devices.

ISSN:0021-8979    

DOI:10.1063/1.1714512

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Factors which affect the superconducting transition temperature (Tc) of thin tin films are of considerable importance in the design of thin film devices. This paper reports an investigation of one such factor, the stress state of the film. Two approaches were used. First, the transition temperature was correlated with the differential thermal contraction between film and substrate. Six different types of glass were used for substrates, and the six films were evaporated simultaneously to ensure similar conditions of evaporation. Secondly, a substrate‐bending technique was used to stress the film while holding it near its transition temperature. For both of these methods, shifts of the transition temperature greater than 0.1°K have been observed. However, it was found that agglomeration of the film can greatly reduce the dependence of the transition temperature on stresses transmitted to the film by the substrate.When agglomeration was negligible, both these approaches yielded a linear increase inTcwith tensile strain. Values fordlnTc/dlnvwere obtained, wherevis the volume of the tin film. The average values were +8.6 from the differential thermal contraction measurements, and +8.1 from the substrate bending measurements. These results are in reasonable agreement with the properties of bulk tin (dlnTc/dlnv=+7.5). However, the films were able to withstand tensile stresses more than an order of magnitude greater than the elastic limit of bulk tin and still recover their original properties upon relaxation.

ISSN:0021-8979    

DOI:10.1063/1.1714513

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The origin and reactions of dislocations in silicon web‐dendrite crystals are discussed. In particular, x‐ray topographs are compared with etching results. Dislocations having [21¯1¯] axes or ⟨110⟩ type axes have been characterized. In the former case, normal edge and 20° dislocations are seen; however, an apparently new dislocation with a [21¯1¯] axis and [101] type or [110] type of Burgers vector has also been observed. Dislocations having a [11¯0] axis and [110] Burgers vector have been identified and associated with the Cottrell‐Lomer reaction. The presence of multiple twin planes parallel to the growth direction of the web, accompanied by regions of very high dislocation density near the dendrites, increases the probability of certain dislocation reactions.

ISSN:0021-8979    

DOI:10.1063/1.1714514

出版商:AIP    

年代:1965

数据来源: AIP