摘要:

Ann‐p‐nheterojunction structure, formed by the epitaxial growth ofn‐Ge on ap‐GaAs substrate having a diffusedn‐GaAs region on the opposite face, has been employed to convert 1.5‐&mgr; radiation incident on then‐Ge face to 0.9‐&mgr; radiation emitted from then‐GaAs face. The internal quantum efficiency of then‐Ge,p‐GaAs heterojunction is 0.62; the spectral response of the heterojunction is typical of photon effects in Ge. The internal wavelength conversion efficiency is 2.8×10−5, limited principally by the low electroluminescent quantum efficiency of the GaAsp‐njunction at low injection current densities.

ISSN:0021-8979    

DOI:10.1063/1.1709748

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Current saturation and the accompanying current oscillation in CdS are studied by measuring the spatial electric‐field distribution as the current decays from its initial Ohmic value to its final saturated value. The initial saturation of the current and subsequent damped oscillation are found to be caused by the presence of moving high‐field domains which propagate at the acoustic‐wave velocity. The detailed behavior of these domains indicates that they are packets of high acoustic‐energy density. As the oscillations damp and the current saturates, the moving domains apparently give way to a competing process. In the current‐saturated condition, only a stationary high‐field region remains. The field distribution in CdS crystals having the drift‐currentparallelto the hexagonal axis is also explored in some detail. The results indicate that in these samples the current saturation is caused by the amplification of shear waves which propagate predominantly at an angle of ∼30° with respect to the hexagonal axis.

ISSN:0021-8979    

DOI:10.1063/1.1709749

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Plasma temperatures generated by focusing ruby‐laser giant pulses on surfaces of Be, Al, and Pb in a vacuum were measured as a function of time and giant‐pulse intensity. The monochromatic emission intensities of the plasmas (relative to those obtained with a standard source) were measured at wavelengths ranging from 4000 to 10 500 Å, and the temperatures were then calculated from the Planck function. It was found that the plasma temperatures achieved with the lighter elements were hotter and had greater rates of increase with laser intensity. However, the rates of increase were proportional to only the 0.5 power of the laser intensity or less, and the difference in temperatures between target materials was not very great. Temperatures as high as 8×105°K were achieved with beryllium.

ISSN:0021-8979    

DOI:10.1063/1.1709750

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Intrinsic degeneracy occurs in semiconductors in which (&Dgr;E/kT) is sufficiently small that the Fermi level is close to one or both band edges. Since studies of the Hall coefficientRand the conductivity &sgr; are often used to investigate such semiconductors,R, &sgr;, and their variation with temperature have been calculated for a simplified model of a degenerate intrinsic semiconductor. This model included spherical energy surfaces, a parabolic density of states, predominance of acoustic phonon scattering, and a linear variation &Dgr;E=E0+&agr;Tof the energy gap with temperature. It was found thatRand &sgr; differ significantly fromR0and &sgr;0, the values predicted by classical statistics. (R/R0) and (&sgr;/&sgr;0) are shown as functions ofTfor several values of the parameters &agr; and (mp/mn), wherempandmnare the hole and electron effective masses. It is also shown that plots of ln |R|T3/2and of ln&sgr; vs (1/T) are nonlinear in the degenerate case and do not have the constant slope, equal to (±E0/2k), respectively, predicted by classical statistics. The results and their bearing on the analysis of experimental data are discussed in terms of the degeneracy of the semiconductor.

ISSN:0021-8979    

DOI:10.1063/1.1709751

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Transmission Kikuchi patterns at 80 keV from wedges of germanium have been measured with high angular resolution. Linewidths are compared with the Fourier potential calculated from a simple coherent‐elastic‐amplitude model. Germanium shows a higher experimental curve of scattering amplitude per unit cell volume than silicon, as may be expected from its greater atomic scattering potential. Suppressed contrast is found for the (111) reflection; this is interpreted as an overlap between the halves of the line‐pair or band.

ISSN:0021-8979    

DOI:10.1063/1.1709752

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The widening of thep‐njunction of a semiconductor is viewed as due to simultaneous diffusion and drift of the impurities. Rigorous first‐order differential equations for the variation of the space‐charge width with time are given. The equations are only dependent, except for an integral term, on the concentrations at the edges of the space‐charge region. Exact solution of the system is always possible for short time if the initial concentration profile is known. This has been done for a few cases.

ISSN:0021-8979    

DOI:10.1063/1.1709753

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The effects of irradiation with 1.17‐ and 1.33‐MeV60Co gamma rays, 0.662‐MeV137Cs gamma rays, and thermal neutrons on the carrier concentration inn‐type CdS and CdTe have been studied by means of Hall‐effect measurements. Irradiation of these materials at room temperature did not introduce any new energy levels in the range from 0.02 to 0.2 eV below the conduction band (the range accessible by experiment), although the density of levels initially present in this interval was altered and, under certain conditions, deep‐lying acceptor states were produced. The most significant observation was the change in the nature of the effect as the energy of the incident gamma rays was changed. For example,137Cs photons introduce acceptors in CdS and donors in CdTe, while60Co photons produce the inverse effect. Atomic displacement calculations indicate that the lower‐energy137Cs photons should preferentially displace sulfur atoms in CdS and cadmium atoms in CdTe; the opposite is calculated for60Co. Hence, these studies suggest that the net result of displacement of a chalcogenide atom is acceptor introduction, with donor introduction resulting from displacement of the cadmium atom. Thermal neutron irradiation of both materials introduces acceptors.

ISSN:0021-8979    

DOI:10.1063/1.1709754

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The relationship of the electrical contact between metal and CdS to the piezoelectric properties was investigated. The influence of the base metal on the crystallographic orientation of the CdS film and the nature of the electrical contact is demonstrated. By measurements of capacitance andI–Vcharacteristics, gold is shown to produce a Schottky barrier and aluminum an Ohmic electrical contact with CdS thin films. The effect of the depletion layer generated by the Schottky barrier on the acoustical output of CdS transducers is shown.

ISSN:0021-8979    

DOI:10.1063/1.1709755

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A theoretical estimate is made of the change in output voltage to be expected when a W/W‐26Re thermocouple is exposed to thermal neutrons, causing some of the rhenium to be transmuted to osmium. The estimated drift may be fairly large: as much as 9.1% when ⅓% of the rhenium atoms are transmuted for a couple measuring a nominal temperature of 1800°C.

ISSN:0021-8979    

DOI:10.1063/1.1709756

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A surface diffusion model for filamentary crystal growth from the vapor phase is presented which accounts for extensive growth normal to the surface. The model is based on the mechanism by which adsorbed atoms are incorporated into surface steps and the anisotropy associated with the capture process. It is shown that filamentary crystals may be initiated at a variety of surface structures including dislocations or impurities but that neither of these is prerequisite. Rather, filamentary crystal growth depends on mobility differences of atoms adsorbed on various crystal planes and the mechanism of capture at surface steps. Results of computer calculations simulating filamentary crystal growth are presented.

ISSN:0021-8979    

DOI:10.1063/1.1709757

出版商:AIP    

年代:1967

数据来源: AIP