摘要:

A series of experimental measurements of the yield of O3in nuclear‐induced O2and O2‐SF6discharges are reported. The discharges were created by bombardment with energetic particles from the10B(n,&agr;)7Li reaction. Continuous irradiation at dose rates of 1015–1017eV cm−3 s−1and pulsed irradiation (∼10 ms FWHM) at a peak dose rate of ∼1020eV cm−3 s−1were conducted. At the lower dose rates, the addition of SF6generally increased the ozone yield due to the slowing of ozone destruction by negative oxygen and ozone ions. In contrast, at the high dose rates, the ozone concentration decreased due to SF6suppression of atomic oxygen formation by ion–ion recombination. A numerical model was developed and tested against experimental conditions. This model indicates that the steady‐state ozone concentration was limited by the reaction O−3+O3→2O2+O−2with a rate coefficient of ∼1×10−12cm3 s−1. In addition to dose rate effects, pressure and temperature effects on ozone production are discussed and methods for increasing the ozone yield are suggested.

ISSN:0021-8979    

DOI:10.1063/1.337364

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Nonplanar morphology and compositional inhomogeneity are observed in GaAs1−xPxsuperlattices when the phosphorus content is substantially different in adjacent sublayers. The main characteristic feature of the distortion is a series of ribbonlike regions running through the superlattice which etch at a faster rate and contain more phosphorus than the surrounding material and are also the source of clusters of dislocations. Morphological stability and a general decrease in dislocation density can be effected by decreasing the interlayer strain, i.e., compositional difference, between the superlattice sublayers.

ISSN:0021-8979    

DOI:10.1063/1.337365

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The pressure dependence of the optical phonons in LiNbO3to 21 GPa and in LiTaO3to 10 GPa has been investigated by Raman spectroscopy, using the diamond anvil cell. All the observed modes increase in frequency with pressure, and no mode softening occurs. This is in contrast to the behavior observed in BaTiO3and PbTiO3, which are well‐known displacive‐type ferroelectric. It is suggested that this difference in pressure behavior may stem from a different type of phase transition in LiNbO3and LiTaO3, namely the order‐disorder type.

ISSN:0021-8979    

DOI:10.1063/1.337366

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

By reference to recent data on amorphous silicon, it is shown that the measurement of the temperature dependence of the current in the space‐charge‐limited regime leads to a determination of the trap density and distribution, and the product of the free‐carrier mobility and density of extended states.

ISSN:0021-8979    

DOI:10.1063/1.337790

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The primary ion beam column of a combined secondary ion/sputtered neutral mass spectrometer is used forinsituion implantation of precise amounts of a given species superimposed as an internal standard upon its residual concentration. Subsequent depth profile analysis is done in the instrument after switching to another primary projectile. It is shown that concentrations can be determined with an accuracy of 4% from the knowninsituimplanted fluence by comparing the original and the added amounts. In this way, the helium concentration in a silicon sample (produced by external implantation) and the interfacial oxygen concentration between an amorphous and crystalline Si layer are determined quantitatively.

ISSN:0021-8979    

DOI:10.1063/1.337367

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Transport currents in one leg of a cross strip superconducting‐normal metal‐superconducting Josephson junction have been used to bias the current‐voltage characteristics of the junction, and hence use the junction as a control element. The bias current creates a magnetic field in the junction, which in turn modulates the Josephson currents. As the bias current causes successive flux quanta to enter the junction, the Josephson critical current shows current‐voltage curves similar to the resistively shunted junction model and a normal Fraunhofer pattern. Values of the bias are relatively small because the junctions are so thick. A detailed study of the junction voltage as a function of bias current shows reentrant superconductivity as successive vortices enter the junction.

ISSN:0021-8979    

DOI:10.1063/1.337368

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Radiation sensing field‐effect transistors operated at zero bias show a low‐dose response that is roughly linear in the thickness of the gate oxide. The same devices show a thickness squared dependence if a bias is applied during the irradiation. This effect can be explained by examining the effect of diffusion and electron trapping on the buildup of net positive charge in the gate oxide.

ISSN:0021-8979    

DOI:10.1063/1.337369

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The use of a sputtered silicon film as a new type of etching mask is reported for the first time. Its desirable properties arise because of similar material characteristics (thermal expansion coefficient, crystal structure, smaller misfit factors) and different etching behavior as compared to gallium arsenide. These properties are studied and utilized in the fabrication of GaAs/GaAlAs double heterostructure (DH) ridge waveguide devices.

ISSN:0021-8979    

DOI:10.1063/1.337370

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The interactions between Au and Cu across a Ni barrier layer have been studied using a wide range of Ni thickness. Above 300 °C, extensive interdiffusion between Au and Cu has been observed, with little involvement of the Ni layer. The interdiffusion between Au and Cu results in a nearly continuous change and uniform distribution in composition for both the parent Au and Cu layers, different from those of the binary Au/Cu system. Reaction mechanisms involved are suggested, and the impact of such interactions on the packaging metallurgy is discussed.

ISSN:0021-8979    

DOI:10.1063/1.337371

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

An extended Norde plot is described which makes it possible to determine the series resistance, barrier height, and ideality factor from oneI‐Vmeasurement of a Schottky barrier diode. A theoretical derivation is performed followed with experimental data, which demonstrates the feasibility of the method.

ISSN:0021-8979    

DOI:10.1063/1.337372

出版商:AIP    

年代:1986

数据来源: AIP