摘要:

A self‐consistent fluid model has been used to analyze streamer arrival at the cathode and its transformation to the stationary cathode fall in a positive point–to–plane corona discharge in N2at 26.7 kPa. The model is based on a description of the electron and the ion kinetics by one‐dimensional continuity equations coupled with Poisson’s equation. The ions and electrons are assumed to be limited to a cylindrical channel with fixed radius and the field is computed using the method of disks. The computed current induced by the streamer–cathode interaction with a small cathode probe is compared with that measured experimentally. The cathode probe signal consists of an initial sharp current spike due to the displacement current followed, some 20 ns later, by a lower current hump due to the ion arrival at the cathode. The current signal is relatively insensitive to changes in the secondary electron emission coefficients. The results obtained indicate that the intense ionization and associated light flash experimentally observed near the cathode at the streamer arrival are not, as generally accepted, due to an intense electron emission but due to a sudden increase in the multiplication factor and a release of electrostatic energy accumulated in the streamer channel–cathode system. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359940

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A transient model of a low‐pressure Cs‐Ba diode which operates in a collisionless Knudsen mode is developed and benchmarked with experimental measurements. The model couples the external circuit to the plasma discharge in the diode. The model calculates the electron energy, plasma density, densities of ground state and first four excited states of neutral Cs atoms, sheath potentials, Cs coverage on the electrode surfaces, forward voltage drop, and discharge current as functions of time, as well as the current‐voltage (I‐V) characteristic of the diode. Calculated terminal voltage and current characteristics are in good agreement with experimental values. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359941

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Experiments are performed using Langmuir probes to measure the plasma parameters in both steady‐state andI‐Vmodes in a low‐pressure Cs‐Ba diode. The data show that at low discharge currents the electron energy distribution function is nonMaxwellian due to the presence of an electron beam from the emitter. Also, the plasma properties were nonhomogeneous across the 1 mm diode gap; the electron temperature was 10%–15% higher and the plasma potential ∼1 V higher near the emitter, and the plasma density was a factor of three higher near the collector. The good agreement between calculations and experiment, in spite of the presence of the electron beam from the emitter, suggested that the beam electrons do not undergo collisions with Cs atoms in the gap. ExperimentalI‐Vcurves showed the presence of two different thermal emission currents, each corresponding to a different emitter work function, at the beginning and the end of theI‐Vpulse. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359942

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Work has been carried out to optimize the operation of a high‐voltage trigatron switch. It is demonstrated here that the trigatron can operate in two different modes depending on the route of the initial breakdown. This initial breakdown can occur either to the adjacent electrode or to the opposite electrode. It is shown here that, for a given switch, the mode of operation depends only on the ratio of trigger voltage to working voltage. The optimization was based upon the suggestion that the optimum operation of a trigatron would occur when the trigger pin breaks down simultaneously to both the adjacent and the opposite electrodes. This occurs for the trigger to working voltage ratio, which results in equal mean electric fields across the main gap and the trigger gap. The experiments were carried out with working voltages,Vg, between −1 and −2 MV and with trigger voltage to working voltage ratios of between −2% and −8%. It is shown that the minimum delay and jitter figures are indeed obtained with the trigger voltage closest to this optimum value,Vt*. For the switch used here, this corresponded to a ratio ofVt*/Vg=−3.4%. A single switch was operated for two hundred shots with a working voltage of −2 MV and the optimum trigger voltage and gave an average delay of 44 ns with an overall jitter of 4.4 ns. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359943

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A point‐defect‐based model for the stress effects on dopant diffusion in silicon is presented. Variations in binding energies and diffusivities of dopant‐defect pairs under hydrostatic pressure are modeled, and a pressure‐dependent dopant diffusion equation is derived. New experimental work was performed on boron pileup near dislocation loops, and compared to the model. Qualitative agreement is possible, which suggests that stress might be a significant effect in scaled modern device structures. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359944

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We propose a model for point‐defect‐assisted transient diffusion and activation of high‐dose boron implants in silicon. To model transient diffusion, a nonlinear equilibrium clustering model for point defects is used. The activation of boron is modeled as a Fermi‐level‐dependent transformation of inactive dopant clusters to substitutional atoms. Comparison with experimental data shows that this approach can provide a description of both rapid thermal annealing and long‐time furnace annealing steps, with an excellent predictive capability for both chemical and electrically active profiles. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360748

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

This article compares the nature of phosphorus antisite defects in as‐grown and neutron irradiated GaP crystals. Electron spin resonance studies indicate that these defects in both kinds of crystals have identical close neighbors consisting of four phosphorus atoms. Neutron irradiation of GaP introduced an additional defect (called WA1), which is linked to a gallium antisite. Characteristic absorption bands and conductivity of neutron irradiated GaP crystals are discussed as well. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359945

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The deep level transient spectroscopy technique has been employed to follow closely the effect of 1–300 Mrad60Co &ggr; irradiation on the deep electron traps in undoped vapor‐phase‐epitaxyn‐type GaAs. The 1 Mrad &ggr;‐irradiated Schottky device was identical to the as‐grown or control device, with only two electron traps EL2 (Ec−0.820 eV) and EL3 (Ec−0.408 eV) detected. At a &ggr; dose of 5 Mrad, two additional electron traps EL6 (Ec−0.336 eV) and E2 (Ec−0.128 eV) were observed. As the &ggr; doses were increased to ≥10 Mrad, a third electron trap E1 (Ec−0.033 eV) was observed, and the single exponential EL2 capacitance transient became a double exponential, indicating two deep levels lying atEc−0.820 eV (EL2/EL2‐A) andEc−0.843 eV (EL2‐B). The trap concentration of EL2‐A remained unchanged up to a &ggr; dose of 50 Mrad before starting to increase slowly as the &ggr; dose was increased to ≥100 Mrad. In contrast, the EL2‐B trap concentration was found to increase by 32 times, reaching 2.6×1014cm−3at 300 Mrad from a low 8.0×1012cm−3at 10 Mrad when it was first observed, whereas for the 1 MeV electron irradiation with low electron fluence of 1014e cm−2, the EL6, E2, E1, and the double exponential EL2 were detected at the same time. There was no sign of EL2‐B, EL3, EL6, E2, or E1, but an additional broadUband was observed after irradiation with 1 MeV neutrons. The results of the &ggr; and neutron irradiation suggest that the presence of the double exponential EL2 transients is not related to either EL6, E2, E1, or theUband, and is unlikely to be due AsGa→VGa+Asibut is probably caused by the AsGacomplex defects involving an irradiation defect. The defect concentration of trap E1 increased strongly from 5.4×1013cm−3at 10 Mrad to 9.3×1014cm−3at 100 Mrad, and E2 increased from 2.1×1013cm−3at 5 Mrad to 6.7×1014cm−3at 100 Mrad. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359946

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We calculated the elastic strain relaxation in wurtzite GaN–AlN–GaN semiconductor–insulator–semiconductor (SIS) structures. Elastic strain tensor components, elastic energy, the density of the misfit dislocations, and the other parameters of the system were obtained as functions of the AlN layer thickness. Theoretical values of the elastic strain relaxation are in satisfactory agreement with experimental data extracted from the capacitance‐voltage (C‐V) characteristics of GaN–AlN–GaN SIS structures. Our results confirm that the gradual relaxation process starts from 30 A˚ AlN film thickness. The uniform contributions to the elastic strain tensor components decrease by approximately an order of magnitude when the film thickness increases from 30 to 100 A˚. Commensurate with this decrease is an increase in a nonuniform contribution of the misfit dislocations. The dislocation interactions lead to redistribution of dislocations within the 30–60 A˚ range of AlN film thicknesses. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359947

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The technique of ion‐induced quantum‐well (QW) intermixing using broad area, high energy (2–8 MeV As4+) ion implantation has been studied in a graded‐index separate confinement heterostructure InGaAs/GaAs QW laser. This approach offers the prospect of a powerful and relatively simple fabrication technique for integrating optoelectronic devices. Parameters controlling the ion‐induced QW intermixing, such as ion doses, fluxes, and energies, post‐implantation annealing time, and temperature are investigated and optimized using optical characterization techniques such as photoluminescence, photoluminescence excitation, and absorption spectroscopy. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359948

出版商:AIP    

年代:1995

数据来源: AIP