摘要:

Experimental studies of MOS capacitors subject to linear voltage ramps so as to drive the devices into the non‐steady‐state are presented. The resulting current‐voltage characteristics, which are extremely rich in structure, are shown to be strongly dependent on temperature and voltage sweep rate. Furthermore, the characteristics, which are related to electron‐hole pair generation in the depletion region of the silicon, correlate extremely well with the appropriate theoretical curves over a wide range of temperatures and sweep rates. Consequently, the technique is shown to be a sensitive means of determining information on the trap parameters of generation centers present in the silicon bulk.

ISSN:0021-8979    

DOI:10.1063/1.326127

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Variations of barrier heights with heat treatment are observed on Au/(n‐type) InP Schottky diodes. Then‐type InP wafers used are vapor epitaxially grown ({100} face oriented) and have carrier concentrations in the range 4×1015to 2×1016cm−3. Before the deposition of the metal, the surfaces are chemically etched in a bromine‐methanol mixture. Electrical characteristics are reported as a function of isochronous heating cycles from 120 to 340 °C, using conventional Schottky barrierI‐VandC‐Vanalysis. The barrier heights are in the range 0.42–0.49 eV. Degradation characteristics and decreased barrier heights are observed after a 340 °C heat treatment in N2with a residual O2atmosphere. Distribution profiles of elemental species obtained by Auger electron spectroscopy associated with an Ar+‐ion‐beam sputtering show the interdiffusion between the metal and InP as a function of the heat treatment: out‐diffusion of In and O as a solid solution of In2O3in the Au film and Au and O diffusion through the Au/InP interface at 340 °C.

ISSN:0021-8979    

DOI:10.1063/1.326128

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Capacitance (C‐V) and capacitance derivative (C′‐V) measurements have been taken on MIS Hg0.8Cd0.2Te‐ZnS devices. The surface‐state distributions are determined from a digital simulation program describing the characteristics of an MIS structure with a semiconductor having a nonparabolic conduction band and a parabolic valence band. A combination of a nonuniform acceptor surface‐state distribution centered at the conduction band edge and a nonuniform donor surface‐state distribution centered at the valence band edge is necessary to fit the experimentalC‐VandC′‐Vdata. From flat‐band voltage versus insulator thickness plots, the work function for Hg0.8Cd0.02Te is 4.23±0.67 eV. The immobile trapped charge density in the samples studied has an average value of 1.66×1012cm−2.

ISSN:0021-8979    

DOI:10.1063/1.326129

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Calculations of domain wall energies, effective threefold anisotropy, and graphical solutions of the equilibrium magnetization directions are carried out for a (111) implantation layer in the implanted‐disk bubble configuration. Comparison is made with the observations of Lin, Dove, Schwarzl, and Shir.

ISSN:0021-8979    

DOI:10.1063/1.326130

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The wall velocity of a nonimplanted garnet film is measured carefully by the collapse method for the drive field higher than the Walker critical field. The wall displacements (&Dgr;R) were plotted as a function of the pulse width (&tgr;) or the pulse field strength (Hp). The data (&Dgr;Rversus &tgr;) show that the discontinuous phenomena continue from the fast‐velocity region I to the saturation‐velocity region III via the oscillatory region II. For region II, the periodic time (T) of the oscillatory motion indicates the relationT= (2&pgr;/&ggr;)(1/Hp) (&ggr;=1.3×107rad/sec Oe) versus the drive fieldHp. The others (&Dgr;RversusHp) demonstrate clearly also the oscillatory mode and the relation H˜= (2&pgr;/&ggr;)(1/&tgr;) between the oscillation period for field strength (H˜) and the pulse width (&tgr;) for region II. We say the ’’2&pgr;‐mode’’ oscillation for the mode of region II. This 2&pgr;‐mode oscillation can be explained neither by Walker model for the untwisted wall nor by the horizontal Bloch line model for the twisted wall. Here, we propose a hypothesis: the coherent precession of spins in the wall occurs with maintaining the twisted structure of the static state by applying the drive field pulse sufficiently higher than the critical field (regions I and II), and then the mode changes to the incoherent precession mode (region III).

ISSN:0021-8979    

DOI:10.1063/1.326131

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We present the results of the magnetic measurements on (GdxY1−x)Fe2compounds between 4.2 and 1300 K. Forx≳0 typical magnetization curves characteristic of ferrimagnetic ordering are evidenced. The reciprocal susceptibility follows a Ne´el‐type relation. The composition dependence of the magnetic interactions in the system is analyzed. The iron moment scales linearly with the exchange field acting on Fe atoms. The correlation between the Fe57hyperfine field and the electronic momentMFeat the iron site in a number of rare‐earth (yttrium) compounds is presented. A simple linear relation is found. Based on the above data a comparison between the thermal variation of iron magntization, calculated using the Ne´el model, and that deduced from the hyperfine field is made. The data evidence that the molecular field model describes rather well the magnetic behavior of these systems. The results of ferromagnetic‐resonance measurements inXandKbands are presented. The data are analyzed using the Vangsness relation. Finally, the magnetic behavior of iron atoms in these compounds is discussed.

ISSN:0021-8979    

DOI:10.1063/1.326132

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The low‐temperature (LT) TSD spectra of water and methyl alcohol adsorbed on Aerosil have been experimentally resolved. The variation of the area under the peaks with relative pressure (partial dielectric isotherms) have been studied and correlated with the adsorption isotherms. The relationship between the peak areas and the adsorbed amount suggest peaks I, II, and III be attributed to the dipolar polarization of the water or methyl alcohol molecules H bonded to the surface OH groups. The lengthening of the relaxation times as compared with that of the bulk liquid is explained in terms of entropy change on adsorption. In contrast, peaks IV and IV* are probably due to the dielectric polarization into small‐size molecular aggregates. The fine structure of the TSD spectrum of adsorbed water on Aerosil is also compared with hertzian spectra of water adsorbed on silica.

ISSN:0021-8979    

DOI:10.1063/1.326133

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The piezoelectric activity of eight vinylidene fluoride–co‐tetrafluoroethylene polymers was studied to further our understanding of this phenomenon. Film compliance, density, degree of crystallinity, and piezoelectric activity were measured in this study. It is shown that the piezoelectricdconstant is calculable from a molecular dipole theory where the polarization is derived using a cavity reaction field.

ISSN:0021-8979    

DOI:10.1063/1.326134

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The spectral dependence of the absorption coefficient of silicon for photon energies up to 2.7 eV was determined for several temperatures in the range 298–473 K. The effect of a temperature increase appears as a red shift of the absorption spectrum. The magnitude of the shift is larger than that of the fundamental energy gap, increases with increasing photon energy in the range 1.1–1.7 eV, and is constant for energies greater than 1.7 eV. A phenomenological expression deduced by analysis of the data may be used to calculate &agr; (E) at elevated temperature, given &agr; (E) at room temperature. The reflectance was also measured at 299, 413, and 516 K in the photon energy range 2.5–3.8 eV.

ISSN:0021-8979    

DOI:10.1063/1.326135

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Effects of photoirradiation on amorphous As2Se3and As4Se5Ge1thin films are measured in far‐infrared (ir) experiments. Optically enhanced broadenings of the dominant ir absorption bands, similar to that in amorphous Se‐Ge, are described. The broadening degree seems to correspond to an increased randomness in the bond angle of the pyramidal structure. In amorphous As4Se5Ge1, a localized molecular vibration model, consisting of As‐Se and Se‐Ge bonds, is justified.

ISSN:0021-8979    

DOI:10.1063/1.326136

出版商:AIP    

年代:1979

数据来源: AIP