摘要:

A method for obtaining range distribution for ion beams bombarding semi‐infinite random solids is presented. Calculations are performed for light ions injected into a heavy target (Z≳20). Examples of range distributions for proton projectiles are given together with those obtained from the usual type of calculation where an infinite target is assumed. Pronounced deviations are observed, especially at low projectile energies, where reflected particles penetrating back into the ’’real’’ target cause false particle deposition. At high energies (Lindhard energy parameter &egr;≳10) these deviations diasappear.

ISSN:0021-8979    

DOI:10.1063/1.329278

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The dynamic response of lead targets 0.025 mm and 0.05 mm thick to heating by a 1.0 MeV electron beam for about 50 ns is described. The lead targets were contained between a thin titanium tamping layer and a thick layer of fused quartz. Measured and predicted peak stresses in the quartz for no gap between the lead and the confining surfaces were approximately 12 kbar and agreed within 1 kbar. Peak stresses decreased rapidly with gap size to values, at 0.025‐mm gaps, of about 1 kbar for the 0.025‐mm lead targets and 5 kbar for the 0.05‐mm targets. Predicted and measured values of tamper velocity (momentum) were within 10% only when the lead and confining walls were in close contact. The observed velocities for even very small gaps were substantially below predictions.

ISSN:0021-8979    

DOI:10.1063/1.329279

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The role of the plasma contribution to the heat dissipation during laser annealing of monocrystalline silicon was investigated. The experiments were performed with aQ‐switched ruby laser with a pulse length of 25–30 nsec. It was found that for samples with larger values for the minority carrier diffusion length, the threshold energy for annealing was increased and the depth of melting was reduced. The experimental results were compared with a thermal model which takes into account the modification of the distribution of laser energy coupled to the lattice due to the diffusion of the minority carriers which occurs prior to recombination. It is concluded that, due to the significant reduction of the minority carrier diffusion length which occurs under the exteremely high generation rates achieved during laser annealing, the plasma diffusion does not dominate the thermal behavior. However, the effects of plasma diffusion can be observed experimentally and they should not be neglected in a completed description of the laser annealing process.

ISSN:0021-8979    

DOI:10.1063/1.329280

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

An investigation into the possiblity of inducing a net transport of molecules via their interaction with a propagating surface acoustic wave is reported here. A theory is presented predicting such a transport and giving a formula for the pumping rate of a device consisting of two evacuated chambers connected by a channel of rectangular cross section containing a surface on which a surface acoustic wave is propagating. This formula gives the parametric dependence of the pumping rate on the wavelength, amplitude and velocity of the surface acoustic wave, and the mean molecular velocity of the gas. The results of an experimental investigation are also given. The experiment, conducted with air at approximately 3 &mgr; and a surface acoustic wave on a lithium niobate substrate, confirms the existence of transport and gives a pumping rate which compares favorably with the theoretical prediction. Possible applications of this effect include its use in vacuum technology and studies of surfaces and surface interactions.

ISSN:0021-8979    

DOI:10.1063/1.329281

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The behavior of ITO‐SiOx‐pSi tunneling solar cell (MIS type) under concentrated light illumination is analyzed theoretically. Conversion efficiency as high as 22.7% is predicted at 75×AM1 illumination. At still higher light concentration the efficiency drops mainly owing to the resistance of the SiOxlayer. The numberical calculations show the important role of the interface states in the tunneling process, electrical charge storage, and carrier recombination. Large current flowing through the diode can induce significant quasi‐Fermi level drop across the insulator layer and electric charge storage in the depletion region. The operation of the diode cannot be explained by the standard MIS theory of low current densities. Therefore a more general treatment is presented here.

ISSN:0021-8979    

DOI:10.1063/1.329282

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

To demonstrate the thermal stability of titanium nitride as a high‐temperature diffusion barrier, the TiN‐Ti‐Ag metallization scheme has been tested on shallow‐junction (∼2000 A˚) Si solar cells. Electrical measurements on reference samples with the Ti‐Ag metallization scheme show serious degradation after a 600 °C, 10‐min annealing. With the TiN‐Ti‐Ag scheme, no degradation of cell performance is observed after the same heat treatment if the TiN layer is ≳1700 A˚. The glass encapsulation of cells by electrostatic bonding requires such a heat treatment.

ISSN:0021-8979    

DOI:10.1063/1.329283

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The integrals given by Parketal. in an earlier paper [J. Appl. Phys. 52, 296 (1981)] on 1/f noise are expressed in closed forms and evaluated numerically. The results show how the field dependent mobility affects the number fluctuation model and how the field dependent mobility and the field dependence of Hooge’s parameter &agr; affects the mobility fluctuation model. The latter effect is very strong and results in a large decrease in the noise spectrum at larger values of drain bias, when compared with the elementary theory that neglects these field dependences. For relatively short channels the mobility fluctuation model gives a peak in the noise well before saturation, in agreement with the experiments of Parketal. The effects of the field dependent mobility and of the field dependent &agr; on the noise resistance at saturation are evaluated numerically.

ISSN:0021-8979    

DOI:10.1063/1.329242

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Calculations are made of the rates at which bursts of electronic charge are created in silicon by cosmic rays at sea level. These rates are reduced to two types: point charge bursts and distributed ionization wake bursts. A procedure is shown to evaluate the soft fail rates of simple devices caused by cosmic rays. It is shown that an 8‐M byte semiconductor memory made of 10×10 &mgr;m diodes will have a soft fail rate of about one per day.

ISSN:0021-8979    

DOI:10.1063/1.329243

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

It has become standard practice to apply optimum linear filter theory to the analysis of gravitational radiation detection systems. In this paper, we present an analysis of the signal‐to‐noise ratio (SNR) of a two‐mode resonant detector consisting of a resonant antenna coupled to a resonant transducer. We also present a comparison of the results of this analysis to the performance fo the Stanford 4800‐kg cryogenic gravity wave detector. The analysis given includes all Gaussian noise sources present in the system. These include mechanical and electrical dissipation noise sources as well as amplifier voltage and current noise. The procedure is partly numerical, but it is extremely efficient and allows optimization over a range of design parameters, rather than the case‐by‐case results provided by the usual modelling techniques.

ISSN:0021-8979    

DOI:10.1063/1.329244

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

One of the present authors recently published a theoretical model of a two‐temperature free‐burning discharge. There was a need to obtain a set of measurements under conditions approximating the theoretical assumption of free cooling of the discharge column. Two accessible parameters were chosen for comparison with the theory, namely the electric field and the luminous radius. The results are in good agreement with theory and provide additional evidence that the model may be used with confidence for low‐current nonequilibrium discharge studies.

ISSN:0021-8979    

DOI:10.1063/1.329245

出版商:AIP    

年代:1981

数据来源: AIP