摘要:

Studies of typical DLTS systems using either the dual‐channel boxcar averager or the lock‐in amplifier techniques are presented. The effects of nonzero gate width for the boxcar averager, phase angle adjustment for the lock‐in amplifier, and response time of a typical commercial capacitance meter are investigated. Errors introduced in the measurements by these effects are calculated for typical cases. Measurements of the gold donor level in silicon are presented, along with calculated corrections. We find the corrections to be minimal in the boxcar‐averager method, but significant in the lock‐in amplifier approach.

ISSN:0021-8979    

DOI:10.1063/1.326665

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The molecular stopping cross sections of the organic ring compounds cyclopentane, cyclohexane, cyclooctane, cyclopentene, cyclohexene, 1,3‐cyclohexadiene, benzene, toulene, phenylacetylene, cyclohexanone, andp‐dioxane have been measured for helium ions with energies from 0.3 to 2.0 MeV. It is found that the ring structure of molecules with less than six CH2groups in the ring as well as the nature of the bonds involved correlate with deviations from Bragg’s rule as great as 14.7%. Evidence of resonance in the ring structure which correlated with the stopping cross section of the compound benzene is also observed. A qualitative relationship between chemical bond strain and deviations from Bragg’s rule is given.

ISSN:0021-8979    

DOI:10.1063/1.326666

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Measurements have been made of the functional form of the energy‐differential cross sections for carbon, using transmission electron energy‐loss spectroscopy. It is shown that both the characteristicKedge and the background, prior to theKedge, can be represented accurately by functions of the formAE−r, whereEis the energy loss andAandrare constants. The values of the exponent in this expression for theKedge have been compared with calculated values derived from a hydrogenic model and good agreement has been obtained.

ISSN:0021-8979    

DOI:10.1063/1.326667

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A three‐dimensional rf quadrupole ion trap has been constructed to study ion production by electron‐impact ionization. Gases and atoms in an atomic beam can be investigated. The method can be extended to the study of photon ionization and of the production of multiply charged ions by a single collision and/or by step‐by‐step ionization. Total electron‐impact ionization cross sections of helium have been measured and are &sgr;e(350 eV) =0.26(6) ×10−16cm2and &sgr;e(500 eV) =0.21(4) ×10−16cm2. Equations are derived to operate the rf ion trap in the symmetric storage mode.

ISSN:0021-8979    

DOI:10.1063/1.326591

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An analysis is presented for the mutual impedance between two solenoids that are coaxial with a conducting cylinder in relative motion. The formulation is based on the first‐order Lorentz transformation and the results obtained are sufficiently general to encompass any such situation that could arise in nondestructive‐testing schemes. A numerical example, relevant to steel‐wire ropes of 2‐cm radius used in mine hoists, indicates that even with relative velocities as high as 10 m/s, the mutual impedance at 10 Hz differs little from that calculated for zero velocity. However, the nonreciprocal effects could be significant for higher velocities and/or for more highly conducting and larger ropes.

ISSN:0021-8979    

DOI:10.1063/1.326668

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An infinite number of rotationally symmetrical functions &PSgr; (r,z) can be found which approximate a given functionf(z) on the optical axis 0z(randzbeing cylindrical polar coordinates). The &PSgr; (r,z) are given in the form of a finite Fourier‐Bessel series and it is shown how a solution that can be used in electron optical design can be selected by carefully assigning values to the following parameters: the number of terms in the series, the period of the series, and the amount of smoothing introduced. In this way a compromise is established between the quality of the axial approximation, the magnitude of potential gradients to be contended with in zonal regions, and the sizes of apertures allowed. Two‐foil, one‐foil, and open lenses can be modeled, and given axial potential functions can be accommodated which are either (i) analytic, (ii) continuous but with piecewise continuouszderivatives, or (iii) in the form of a set of experimentally determined values. The method requires no matrix inversion, the computer programming is of a simple nature, and memory requirements are modest enough to allow implementation of the program on small desk‐top computers.

ISSN:0021-8979    

DOI:10.1063/1.326669

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The HCl multiline output power of a TE helical laser is enhanced by adding CO2to the H2+Cl2mixture. In single‐line operation, the output powers on the vibration‐rotation lines of the (1→0) band can be increased by a factor of 3 as CO2is added.

ISSN:0021-8979    

DOI:10.1063/1.326670

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

In this paper, detailed comparisons are made between the numerical predictions of a comprehensive KrF kinetics/laser‐model computer code and the experimental results from an e‐beam‐pumped KrF laser. The code and the experimental laser device are described. The inputs to the code are the measured temporally varying e‐beam energy and current density, the laser mixture, the optical‐cavity output coupling, and the optical gain length. Comparisons include laser output power, laser output pulse shape, and KrF* fluorescence from the laser‐cavity sidelight under lasing and nonlasing conditions. Using our numerical model, we have generated a scaling map for the KrF* laser.

ISSN:0021-8979    

DOI:10.1063/1.326646

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Nonradiative recombination processes in GaAlAs double‐heterostructure lasers are examined using luminescence time‐response measurements. Photoluminescence time‐decay data for proton‐bombarded (PB) isotype (p‐type) heterostructures give an effective recombination velocity for the PB region of (7±1) ×105cm/sec. Electroluminescence decay times of laser devices indicate that the interfacial recombination velocity of the anisotype interface (p‐GaAs/N‐GaAlAs) is 1500±500 cm/sec compared with 400±100 cm/sec for isotype (p‐type) interfaces. The contribution of each important recombination process to the laser threshold current is calculated. For devices in which the PB region penetrates into the active layer, recombination in the PB region and interfacial recombination are the major nonradiative paths.

ISSN:0021-8979    

DOI:10.1063/1.326647

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

An electro‐optic waveguide directional‐coupler switch has been fabricated in GaAs by liquid‐phase epitaxy, photolithography, chemical etching, and electroplating. The Schottky electrodes, overlaying each single‐mode rib waveguide, are cut midway along the device length to allow the electrical optimization of each switching state (’’stepped &Dgr;&bgr;’’ configuration) in a wavelength range (1.0–1.3 &mgr;m) useful for optical‐fiber communications. The device exhibits good power isolation for both states (at least 19 dB and up to 32 dB) with reverse driving voltages of less than 30 V, at 1.06, 1.15, and 1.32 &mgr;m. Both states have been obtained at 1.06 &mgr;m by switching one single voltage, a convenient way in spite of some power penalty to take full advantage of the large potential bandwidth (1 GHz) of the switch.

ISSN:0021-8979    

DOI:10.1063/1.326648

出版商:AIP    

年代:1979

数据来源: AIP