摘要:

The preparation of single crystals of black monoclinic and red tetragonal ZnP2from the elements is described. The crystals contain 50 to 100 ppm Si as an impurity. The melting point of monoclinic ZnP2is 992±1°C and of tetragonal ZnP2is 985±1°C. Interplanar spacings are presented for both the red and black polymorphs of ZnP2. Two bands have been observed in the near‐bandgap luminescence of tetragonal ZnP2at low temperatures. Both bands exhibit sharp lines, respectively, near 2.144 and 2.020 eV, due to no‐phonon decay of bound excitons, and contain much fine structure due to associated phonon‐assisted transitions. These spectra are identical with luminescence bands reported by Akopyanet al., but are attributed to recombinations in the ternary compound semiconductor ZnSiP2. Preliminary measurements of the indirect‐type absorption‐edge spectrum at low temperatures indicate that the energy gap of tetragonal ZnP2is close to 2.220 eV at 4.2°K and ∼2.14 eV at 300°K.

ISSN:0021-8979    

DOI:10.1063/1.1659103

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Combined electrical conductivity and thermoelectric power measurements have been made on Eu3S4at temperatures from 100° to 1000°K. These measurements show that the charge carrier concentration in this temperature range is essentially constant. The activation energy for electrical conduction arises, therefore, from the temperature dependence of the drift mobility, and is interpreted as an energy required for the hopping motion of the electronic charge carriers. An abrupt change in resistivity, characteristic of a transition, occurs at about 175°K. The activation energy for conduction above and below the transition is 0.163±0.004 eV and 0.21±0.01 eV, respectively. The Seebeck coefficient data obtained are interpreted in terms of the contribution of the kinetic energy term and the influence of the high charge carrier density on the concentration of available sites.

ISSN:0021-8979    

DOI:10.1063/1.1659104

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The properties of a plasma injected into an insulator or semiconductor are analytically describable if diffusive current flow is neglected. However it is known from experimental and theoretical (computer) studies that the corrections imposed by the dominance of diffusive current flow near the contacts are quite large forL/La<10 and significant even for largerL/La, whereLis the distance between the injecting contacts andLathe ambipolar diffusion length. The regional approximation method is employed to obtain an approximate, but complete analytical description of the injected plasma for the two problems. Satisfactory agreement is obtained with previous computer results of Baron.

ISSN:0021-8979    

DOI:10.1063/1.1659105

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The second law of thermodynamics imposes a limit on the maximum efficiency achievable with any rectifier in converting radiation into dc power. By using the second law and Bose photon statistics, a general expression is derived showing that this efficiency depends upon the bandwidth and effective temperature of the incoming radiation. Only for completely coherent radiation can the conversion efficiency be unity. The theoretical implications are illustrated by examining specific thermodynamic cycles involving idealized recombination diodes and thermodynamically ideal rectifiers. The relationship between minimum bandwidth of radiation and bias voltage in a recombination diode is derived. The connection between conversion efficiency and Carnot efficiency is made clear.

ISSN:0021-8979    

DOI:10.1063/1.1659106

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The intrinsic carrier concentration of holes in InSb has been redetermined from the temperature variation of the Hall coefficient without the assumption of acoustic mode scattering. Seven samples were used, threeptype and fourntype. The best statistical fit to the data yieldedni=5.76×1014T3/2exp(−0.129/kBT)over the temperature range 150°≤T≤300°K. Error analysis indicatesniis accurate to within one percent. The heavy‐hole band structure proposed by Kane was used to derive a theoretical expression for the heavy‐hole density of states mass which was then estimated from the value ofnidetermined experimentally. At low temperatures the mass was found to be 0.430m0and to increase with increasing temperature. When the mass value reported here was compared to cyclotron resonance data, agreement was obtained.

ISSN:0021-8979    

DOI:10.1063/1.1659107

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Epitaxial films of CdS were grown on CdS, ZnS, GaAs, Ge, mica, and SrF2substrates using a chemical transport reaction. Electron diffraction, ion blocking and scattering, microscopy, and etch studies of the CdS films were carried out. The surface morphology of the films was studied. A correlation between some structures on the surface of the films and the experimentally and theoretically derived equilibrium forms of CdS crystals was noted. It is concluded that the principal growth mechanism of the epitaxial CdS films is through surface nucleation.

ISSN:0021-8979    

DOI:10.1063/1.1659108

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The Hall effect and resistivity have been measured as a function of temperature for lightly Zn‐doped GaAs of better quality than previously available. Analysis of the Hall coefficient data yields activation energies which change with doping level. These results, along with earlier results on more heavily doped samples, can be represented byEA=0.0308−2.34×10−8(NIA)1/3eV. The Hall mobility as a function of temperature leads to &mgr;L=400(300/T)2.41for the lattice mobility ofp‐type GaAs.

ISSN:0021-8979    

DOI:10.1063/1.1659109

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The transport of electrons across the space‐charge region of ap‐njunction is examined by means of the exact solution of the time‐dependent Boltzmann equation in which the scattering integral is written in terms of the relaxation time approximation. The relaxation time approximation is only valid for elemental semiconductors over the range of temperatures where the device is normally used, and could also be valid for polar semiconductors but only at high temperatures. It is shown that for transition regions which are thick compared to the mean‐free path the effective mobility of the electrons is the high field mobility (exactly the same results are obtained as those derived by Gunn), however when the space‐charge region width is less than the mean‐free path the distribution function is more nearly that obtained for low fields.

ISSN:0021-8979    

DOI:10.1063/1.1659110

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Carrier mobility variations were measured for electrons in silicon inversion layers. Near liquid‐helium temperatures and with electron densities less than about 2×1012cm−2, the mobility increased with field and temperature. Correlation of the electron temperature with field indicates that &Dgr;Tvaries with the field approximately asF3/2. Temperature dependence of the amplitude of the oscillatory magnetoconductance gave similar consistent results. At very high fields, the mobility decreased at all temperatures and electron densities. The electron drift velocity was measured for different surface orientations, substrate dopings, and ambient temperatures from 4.2° to 300°K. The drift velocity was found to saturate for fields greater than a few times 104V/cm, depending upon the low field mobility, and was found to be lower than the reported bulk values. For (100), (111), and (110) surfaces, the limiting velocities at 300°K are (6.5±0.5) × 106, (5.5±0.5) × 106, and (4.0±0.5) × 106cm/sec, respectively.

ISSN:0021-8979    

DOI:10.1063/1.1659111

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

In this work the possibilities of three‐ and four‐stage Bennett‐type aperiodic rf mass spectrometers with energy modulators of 5 and 7 grids have been explored. The expressions for the energy gain, resolving power, harmonics, and their relative peak heights have been obtained. The oscillatory behavior of the energy‐modulating functions has been analyzed using an IBM 1620 Computer, and graphical representations are given which permit the determination of the energy interval over which the analyzer can be operated. Resolution for the most favored combinations of stage separations has been calculated atVr1and 90&percent; values of the retarding voltage level, A grid with improved microoptics and relatively higher ionic transmission coefficient has been developed for use in rf mass analyzers.

ISSN:0021-8979    

DOI:10.1063/1.1659112

出版商:AIP    

年代:1970

数据来源: AIP