摘要:

&ggr;‐ray irradiation with doses up to 8 × 106rad produces no significant change on either theC(V) or theG(V) characteristics of MOS tunnel junctions with intermediate oxide thicknesses (40–60 Å), whereas the expected flat‐band shift toward negative electrode voltages occurs in control thick oxide capacitors. A simple tunneling model would explain the results if the radiation‐generated hole traps are assumed to lie below the valence band of the silicon. The experiments also suggest that the observed radiation‐generated interface states in conventional MOS devices are not due to the radiation damage of the silicon surface.

ISSN:0021-8979    

DOI:10.1063/1.1662978

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Heterostructure injection lasers in which the GaAs active region is the center layer of a five‐layer dielectric slab waveguide have been investigated. The GaAs active layer is bounded on each side by an AlxGa1−xAs layer to confine the carriers. The two outside layers which are AlyGa1−yAs(y>x) confine the optical field. Lasers with this structure have been fabricated and room‐temperature threshold current densitiesJth300as low as 650 A/cm2have been obtained for 1‐mm cavity lengths. Differential quantum efficiencies &eegr;Dfor these separate optical and carrier confinement heterostructure (SCH) lasers were higher than generally encountered for double‐heterostructure (DH) lasers with values as high as 65% for[inverted lazy s]300−&mgr;−longcavities. The external quantum efficiency of several typical units was determined as a function of input current, and for one representative unit a maximum value of 39% was obtained at about four timesJth300. Emission in the fundamental TE mode was obtained for symmetrical structures with optical waveguide thicknesses in excess of 1 &mgr; at currents many timesJth300. The angle of beam divergence perpendicular to the junction plane was found to depend on the thickness of the optical waveguidewwith half‐power point values varying from 51° to 33° forwbetween 0.8 and 1.56 &mgr;. Calculation of the optical intensity distributions for the symmetrical SCH structure demonstrated the influence of the AlAs mole fraction and layer thickness on confinement of the optical intensity and suggest that it should be possible to achieve still lower threholds.

ISSN:0021-8979    

DOI:10.1063/1.1662980

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

11B+ions of 1011−1012/cm2were implanted through gate oxides of 800–2000 Å into the channel regions ofp‐channel MOS transistors. For 50‐keV implantation, the dose dependence of threshold voltage could be explained by Swanson and Meindl's theory. In the case of implantation above 100 keV, slight deviation of the threshold voltage from the theoretical values was observed. Corresponding to this, the gate‐oxide‐thickness dependence of the threshold voltage was slightly deviated from the theoretical values in the range of less than 1300 Å. For more than 1500 Å, the measured threshold voltages coincided with calculated values. The energy dependence of the dose limit for ``ability to turn on‐off'' showed good agreement with the curve calculated on the basis of Swanson and Meindl's theory within this experimental error. Source‐drain current in the saturation region was slightly increased with increasing dose at least up to 5 × 1011/cm2, presumably due to the carrier compensation (band bending) and increase of the mobility. No significant change due to the implantation was observed in the breakdown voltages within the examined dose and energy ranges. Device stability was confirmed by the positive or negativeBTtreatments (125°C, 100 h and 300°C, 60 min). Again, no significant instabilities resulting from the implantation process was detected in this experiment.

ISSN:0021-8979    

DOI:10.1063/1.1662981

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A theoretical treatment of the current transport in MSM devices is presented. It is based upon the application of the thermionic diffusion theory to both junctions and makes it possible to relate the current density to the total voltage applied to the device by a single expression valid for any voltage above reach through. So doing, the contributions of the different transport mechanisms, i.e., thermionic injection over the energy barriers at the junctions and drift diffusion within the semiconductor, may be evaluated both for majority and minority carriers. It turns out that before the flat‐band condition the current is limited by transport phenomena in the semiconductor, while above flat band neither mechanism definitely prevails. However, in spite of the different physical models, numerical results are of the same order of magnitude as those obtained by Szeet al.

ISSN:0021-8979    

DOI:10.1063/1.1662982

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

An important consideration in building large‐volume gas amplifiers, given the pulse duration, is the maximum output intensity which the amplifying medium can support. We consider this problem in detail for CO2lasers to be used in laser fusion experiments. We describe a new means of computing properties of the electron distribution function using a Monte Carlo model, and compare computations by this method with a more common Laplace transform technique. The physics of the models is carefully considered, and the previously ignored effect of Penning ionization is shown to be of potential importance. The computations strongly suggest that for a 1.3‐nsec pulse at 10.6 &mgr;, using conventional pumping techniques, an intensity of 2.3 × 109W/cm2results in less than a 10% energy propagation loss, and that an intensity of 3 × 109W/cm2results in more than a 10% loss.

ISSN:0021-8979    

DOI:10.1063/1.1662983

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Experimental observations on the mode structure and beam divergence of a large‐bore high‐power argon ion laser are discussed. The gain medium, 185 cm in length and 12 mm in diameter, is capable of generating a steady‐state multiline multimode laser output of more than 125 W in the blue‐green. Various stable resonance cavity configurations have been investigated. Littrow prism and small aperture have also been used to obtain single‐line and low‐order transverse mode operations, respectively. The beam intensity profiles at two widely separated distances from the output coupling mirror are measured by scanning the beam across a small aperture affixed to a photodetector, using a rotating mirror. The two measured beam diameters are found to increase with the transverse mode volume (or output power) at a nearly constant ratio. The far‐field beam divergence angle deduced from these measurements is found to vary linearly with the initial beam diameter and to be of the order of 1 mrad at the highest output power.

ISSN:0021-8979    

DOI:10.1063/1.1662984

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

This paper describes a double‐stream analysis that can be used to investigate interactions in any finite multiple‐charged drifting particle stream immersed in a finite longitudinal dc magnetic field that is parallel to the drift velocity. The advantages of the analysis are that collisions and longitudinal thermal velocity effects are included along with transverse waves (fast and slow) and space‐charge waves with the only approximations being small‐signal linearization and negligible transverse thermal velocity. In addition, the finiteness of the charged‐particle streams and the boundary conditions are taken into account. The results of the analysis are field expressions which can be used to obtain a determinantal equation in &ohgr; by satisfying the appropriate boundary conditions.

ISSN:0021-8979    

DOI:10.1063/1.1662985

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

We have fabricated small‐area tunnel junctions of a lead‐tellurium‐lead structure. These have been used in conjunction with bulk superconductors to make hybrid quantum interference devices. We have successfully operated these devices at bias frequencies of 30 MHz, 300 MHz, and 10 GHz.

ISSN:0021-8979    

DOI:10.1063/1.1662986

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The internal structure of domain walls in bubble films, their energy, and their velocity‐momentum relationship are calculated for stripe domains of arbitrary period. The results are similar to those derived previously for films containing a single straight wall, provided that the film thickness is in the range preferred for device applications. For thicker films, however, the theoretically calculated properties of stripe‐domain walls differ considerably from those derived on the assumption that only a single straight wall is present in the film.

ISSN:0021-8979    

DOI:10.1063/1.1662987

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A technique for evaluating the optical anisotropy of fine‐grain polycrystalline thin films is developed. This method is applied to MnBi with the low‐temperature NiAs structure. It is estimated that the optical anisotropy is less than half the magneto‐optic effect.

ISSN:0021-8979    

DOI:10.1063/1.1662988

出版商:AIP    

年代:1974

数据来源: AIP