摘要:

When a ferroelectric body attached to one end of a springy rod is switched with an alternating electric field, it oscillates with the frequency of the applied field. This effect was originally reported by Zheludew and he proposed that it might originate in a manner formally analogous to the classical magnetomechanical experiments of Einstein and de Haas. It is shown here as a result of a theoretical and experimental investigation that this is not the case, but that the oscillations are caused by a shearing of the crystal due to a polarization‐induced strain.

ISSN:0021-8979    

DOI:10.1063/1.1702877

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

An investigation of the electrical properties of CdSe thin‐film triodes has demonstrated the existence of shallow trapping levels distributed from 0.02 to 0.06 eV below the edge of the conduction band. These values have been experimentally determined by a combination of optical and field effect techniques. The investigation also indicates that field excitation of electrons from such levels is a fundamental mechanism of operation in the thin‐film field‐effect triode. Close correlation has been obtained between the dependence of device current on applied gate potential and the probability of field excitation of carriers with the field strengths achieved with these values of potential.

ISSN:0021-8979    

DOI:10.1063/1.1702878

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

A photoconductive signal has been observed in ZnO single crystals at 300°K upon illumination with the 6935‐Å laser light from a ruby rod. With a dark current of 2 mA, a typical peak increase in current was 7 &mgr;A.Green luminescence (centered at 5250 Å) excited by the laser light was also detected. The fluorescent intensity showed an approximately second‐power dependence on incident intensity at lower intensities. At higher intensities an approximately fourth‐power dependence was noted. A plausible model is given to account for the second‐ and fourth‐power dependencies in terms of a two‐photon absorption mechanism. Since the absorption coefficient of ZnO for light of wavelength 6935 Å is quite small, the observed photoconductivity and luminescence are very likely associated with the bulk rather than with the surface.

ISSN:0021-8979    

DOI:10.1063/1.1702879

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

A simple physical model is presented which gives the capacitance‐voltage characteristics of a metal‐oxide‐semiconductor structure at high measurement frequencies in excellent agreement with the experimental observations. The model is based on the concept that at high frequencies the minority carriers within the inversion region act as `fixed charges' and so do not contribute to the ac variation of charge within the semiconductor. However, their presence determines the size of the depletion region under the given dc bias and hence the space‐charge capacitance.

ISSN:0021-8979    

DOI:10.1063/1.1702880

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Optical absorption and surface barrier photoresponse measurements have been made on cleaved samples of Mg2Ge. The form of the results obtained from both techniques indicates an indirect transition at approximately 0.54 eV followed by a direct transition at approximately 1.8 eV.

ISSN:0021-8979    

DOI:10.1063/1.1702881

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

The room‐temperature lattice parameter of GaAs doped with Zn, Cd, Te, and Se has been measured with a precision of ±3 parts in 105using an x‐ray powder diffraction technique. Electrical measurements and microscopic examination of samples were used to qualify the measured lattice parameters and allow limits of the solute lattice dilation coefficient (&bgr;) to be calculated. For Zn in GaAs, &bgr;[equal to or less-than]1.2×10−25cm3/atom, for Cd in GaAs, &bgr;[equal to or less-than]1.1×10−24cm3/atom; for Se, &bgr;>1.3×10−24cm3/atom; and for Te, &bgr; >1.7×10−24cm3/atom. Limits of the stresses that could be generated at the onset of the diffusion of Zn, Cd, Te, or Se into GaAs are derived from these &bgr; values. It appears likely that these stresses will be sufficient to cause plastic flow and the generation of large numbers of dislocations for diffusion of any of these elements into GaAs under conditions of high diffusant surface concentration and high temperature. Preliminary experiments show that the diffusion of zinc into GaAs at 1100°C can generate a high dislocation density in the diffused layer.

ISSN:0021-8979    

DOI:10.1063/1.1702882

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

The measurements on the temperature dependency of the Seebeck coefficient and resistivity of sintered specimens of uranium monosulfide, thorium monosulfide, and US‐ThS solid solutions indicate semimetallic and metallic behavior for US and ThS, respectively. The thermoelectric power of US exhibits a weak dependence on temperature and decreases with increasing ThS content; except for initial disordering effects, the resistivity of US shows a similar dependence on temperature and composition. The presence of higher sulfides in US results in a considerable lowering of the Seebeck coefficient with increasing temperature. The figures of merit for US are too low for useful high‐temperature power generation by a factor of approximately ten.

ISSN:0021-8979    

DOI:10.1063/1.1702883

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

This paper discusses in detail the shape of the potential barrier existing between two parallel‐plane metal electrodes separated by a thin insulating film. The emission‐limited current flow between the electrodes is determined for symmetric and asymmetric junctions. The asymmetricJ‐V(current‐voltage) characteristic is of particular interest, as it can be shown that the difference in work function of the two electrodes comprising the junction can be obtained from a perfunctory study of the characteristic. The thermionicJ‐Vcharacteristic is compared to the tunnelJ‐Vcharacteristic. For a temperature of 300°K, and for a barrier thickness less than 40 Å, the tunnelJ‐Vcharacteristic predominates. However, for barrier thickness greater than 40 Å, either the thermionic or the tunnel characteristic can predominate, depending upon the barrier height and the applied voltage. In the case of asymmetric junctions, there may be a reversal of direction of rectification with decreasing temperature. This reversal of rectification may explain the similar effect sometimes observed in tunnel junctions.

ISSN:0021-8979    

DOI:10.1063/1.1702884

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

The effects of the voltage swing, peak current‐to‐capacity ratio (IP/Cjv), zinc concentration, and lithium on the degradation of the peak tunnel current are examined in zinc‐doped GaAs tunnel diodes.

ISSN:0021-8979    

DOI:10.1063/1.1702885

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Single and polycrystalline samples of Cd3P2have been prepared. Undoped samples aren‐type with carrier concentrations between 1017and 1018cm−3. The thermoelectric power of these samples goes up to −170 &mgr;V/°C at 300°K. Mobility values up to 3000 cm2/V sec at 300°K were measured. The mobility of single crystals varies in the extrinsic range near room temperature proportionally toT−1.1(Tis temperature). Optical measurements indicate an optical band gap of approximately 0.5 eV. The results of annealing experiments support the assumption that the high electron concentration of undoped samples is due to phosphorus vacancies. The doping properties of various elements have been studied. Copper introduces what is probably a deep‐lying acceptor level, butp‐type samples could not be obtained.

ISSN:0021-8979    

DOI:10.1063/1.1702886

出版商:AIP    

年代:1964

数据来源: AIP