摘要:

A new type of optical bistable device is demonstrated. We report the first observation of optical bistable switching caused by charge‐induced self‐feedback due to field screening in GaAs/AlGaAs multiple quantum well structures, both at room temperature and at low temperature (110 K). A bias voltage supply is directly connected to thep‐i‐ndiode with the multiple quantum well structure to attain optical bistability. Since no external series resistance is required, the device is attractive from the standpoint of a practical application. The mechanism for the self‐feedback underlying the operation of the device is elaborated. The theoretical consideration about the resolvable spot size on the device operation is shown.

ISSN:0003-6951    

DOI:10.1063/1.103653

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Suppression of the Schottky barrier effect in semi‐insulating GaAs is demonstrated by centering the pump irradiation on the reverse bias crystal‐electrode interface. A photorefractive gain coefficient &Ggr; of 2.7 cm−1is achieved. The irradiation suppression overcomes the need for externally applied ohmic contacts.

ISSN:0003-6951    

DOI:10.1063/1.103654

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Etching of various amorphous polymers by the application of CO2laser radiation (10.6 &mgr;m) is described. By passage of the radiation through a high‐resolution mask in contact with the polymer surface, this ablation can produce images having submicron resolution and good edge acuity. The laser intensity required for ablation is compared for various thermoplastic and thermosetting polymers. Below the required level of intensity, no ablation is observed, but the laser irradiation can result in thermal crystallization. The energy necessary to induce ablation with infrared radiation is comparable to that required for UV decomposition.

ISSN:0003-6951    

DOI:10.1063/1.103655

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have measured Raman spectra of a diamond film prepared on the (111) surface of cubic boron nitride(c‐BN) by the dc plasma chemical vapor deposition method. The polarization property of the Raman line of diamond agrees well with that of LO phonon for the (111) surface ofc‐BN. The agreement between the polarization property of Raman lines of diamond andc‐BN indicates a possibility of the heteroepitaxial growth of the diamond film on the (111) surface ofc‐BN. It is found that the diamond layers onc‐BN are under tensile stress of 2.2×1011dyn/cm2. The value of the corresponding tensile strain agrees well with the lattice mismatch calculated from the lattice constants ofc‐BN and diamond, supporting the possibility of the heteroepitaxial growth of the diamond film. Raman spectroscopy is a powerful technique not only to estimate the stress in the diamond film but also to determine the crystallographic orientation.

ISSN:0003-6951    

DOI:10.1063/1.103656

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Reactive ion etching of Si and SiO2in SF6plasmas in which the samples are mounted on a liquid‐nitrogen‐cooled electrode has been studied. At this temperature SF6condenses on the electrode surface, but it is possible to maintain a plasma. Si etch anisotropy has been demonstrated at low temperature, in agreement with previous studies. Mass spectrometry and optical emission spectroscopy indicate that fluorine is the dominant species in the plasma because SF6and SFxspecies are removed from the gas phase by condensation.

ISSN:0003-6951    

DOI:10.1063/1.104240

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

This letter analyzes the transport of an electron beam that is produced during the conductive phase operation in the cathode fall of a pseudospark or back lighted thyratron for applications that require a high brightness electron source. The beam is estimated to traverse the device without thermalization if the plasma density is ≤2.5×1015cm−3. High brightness electron sources are necessary for various new plasma based devices, and these results encourage consideration of this electron beam as a new candidate for applications including microwave generation sources, electron sources for accelerators, and plasma based accelerators which require improved cathodes.

ISSN:0003-6951    

DOI:10.1063/1.103657

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Experimental results are reported on the transport of an electron beam with current in excess of the vacuum space‐charge‐limited value, in a configuration directly applicable to gyrotron oscillators. The vacuum space‐charge limit is circumvented by the introduction of a neutralizing background plasma which is produced by an array of four plasma guns placed immediately downstream of the electron gun anode.

ISSN:0003-6951    

DOI:10.1063/1.103658

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Experiments in pulsed hollow cathode discharges demonstrate that long‐lived species, with lifetime of the order of seconds, play a significant role in the formation of the discharge in nitrogen. Detailed studies show that the effect is strongest in the hollow cathode region. Similar effects are not observed in hydrogen. A simplified model of the destruction of the N2(A3&Sgr;+u) state has been adopted to study the relevance of this level. The possible roles of the metastables in the formation of pulsed hollow cathode discharges are discussed.

ISSN:0003-6951    

DOI:10.1063/1.103659

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

It is demonstrated that laser‐surface interactions that cause optical surface damage of nominally transparent materials can be investigated by observing the effects of excitation by pairs of picosecond pulses separated by a variable time delay. Laser‐induced emission of neutrals is used as the detection mechanism in the present experiments.

ISSN:0003-6951    

DOI:10.1063/1.103660

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The electrical transport properties of zinc oxide varistors are correlated with the chemistry of their grain boundaries. An adsorbed layer of bismuth, about 5 A˚ thick, is necessary to create potential barriers at the grain boundaries. The height of these potential barriers depends sensitively on the excess amount of oxygen (∼1 monolayer) present at the interfaces between grains. This oxygen enrichment is influenced by thermal processing and by electrical degradation.

ISSN:0003-6951    

DOI:10.1063/1.103661

出版商:AIP    

年代:1990

数据来源: AIP