Boron diffusion into diamond under electric bias

1997 ◽  
Vol 12 (5) ◽  
pp. 1169-1171 ◽  
Author(s):  
T. Sung ◽  
G. Popovici ◽  
M. A. Prelas ◽  
R. G. Wilson ◽  
S. K. Loyalka
Keyword(s):  
Diffusion Coefficient ◽  
Electric Field ◽  
Drift Velocity ◽  
Boron Diffusion ◽  
Diamond Crystals ◽  
Natural Type ◽  
Forced Diffusion

Three natural type IIa diamond crystals were used for forced diffusion of boron. The diffusion was performed under bias otherwise with the same conditions. The boron diffusion coefficient in diamond was found to be 8.4 × 10−15 and 4 × 10−14 cm2/s at 1000 °C, depending on the direction of the electric field. The drift velocity of boron in diamond under 850 V at 1000 °C was found to be about 1.2 × 10−8 cm/s.

Electron drift velocity versus electric field in GaAs

1986 ◽  
Vol 29 (12) ◽  
pp. 1295-1296 ◽  
Author(s):  
Chian S. Chang ◽  
Harold R. Fetterman
Keyword(s):  
Electric Field ◽  
Drift Velocity ◽  
Electron Drift Velocity ◽  
Velocity Versus ◽  
Electron Drift

scholarly journals The effective boron diffusion coefficient in Fe2B layers with the presence of chemical stresses

2012 ◽  
Vol 50 (02) ◽  
pp. 115-123 ◽  
Author(s):  
M. ORTIZ-DOMINGUEZ ◽  
I. CAMPOS-SILVA ◽  
G. ARES DE ◽  
J. MARTÍNEZ-TRINIDAD
Keyword(s):  
Diffusion Coefficient ◽  
Boron Diffusion

scholarly journals Electron Drift And Diffusion In Deuterium At 293°K

1966 ◽  
Vol 19 (6) ◽  
pp. 805 ◽  
Keyword(s):  
Diffusion Coefficient ◽  
Drift Velocity ◽  
Electron Drift ◽  
And Diffusion

The drift velocity and the ratio of diffusion coefficient to mobility have been measured for electrons in deuterium at 293�K over the ranges 0�006 � E/p � 5�0 and 0�006 � E/p � 2�0 respectively. The results are compared with those of other workers.

scholarly journals A comparison study between observations and simulation results of Barghouthi model for O<sup>+</sup> and H<sup>+</sup> outflows in the polar wind

2011 ◽  
Vol 29 (11) ◽  
pp. 2061-2079 ◽  
Author(s):  
I. A. Barghouthi ◽  
S. H. Ghithan ◽  
H. Nilsson
Keyword(s):  
Diffusion Coefficient ◽  
Drift Velocity ◽  
Geomagnetic Field ◽  
Particle Interactions ◽  
Polar Wind ◽  
Adiabatic Cooling ◽  
Simulation Results ◽  
Wave Particle Interactions ◽  
Field Lines ◽  
Velocity Diffusion

Abstract. To advance our understanding of the effect of wave-particle interactions on ion outflows in the polar wind region and the resulting ion heating and escape from low altitudes to higher altitudes, we carried out a comparison between polar wind simulations obtained using Barghouthi model with corresponding observations obtained from different satellites. The Barghouthi model describes O+ and H+ outflows in the polar wind region in the range 1.7 RE to 13.7 RE, including the effects of gravity, polarization electrostatic field, diverging geomagnetic field lines, and wave-particle interactions. Wave-particle interactions were included into the model by using a particle diffusion equation, which depends on diffusion coefficients determined from estimates of the typical electric field spectral density at relevant altitudes and frequencies. We provide a formula for the velocity diffusion coefficient that depends on altitude and velocity, in which the velocity part depends on the perpendicular wavelength of the electromagnetic turbulence λ&amp;bot;. Because of the shortage of information about λ&amp;bot;, it was included into the model as a parameter. We produce different simulations (i.e. ion velocity distributions, ions density, ion drift velocity, ion parallel and perpendicular temperatures) for O+ and H+ ions, and for different λ&amp;bot;. We discuss the simulations in terms of wave-particle interactions, perpendicular adiabatic cooling, parallel adiabatic cooling, mirror force, and ion potential energy. The main findings of the simulations are as follows: (1) O+ ions are highly energized at all altitudes in the simulation tube due to wave-particle interactions that heat the ions in the perpendicular direction, and part of this gained energy transfer to the parallel direction by mirror force, resulting in accelerating O+ ions along geomagnetic field lines from lower altitudes to higher altitudes. (2) The effect of wave-particle interactions is negligible for H+ ions at altitudes below ~7 RE, while it is important for altitudes above 7 RE. For O+ wave particle interaction is very significant at all altitudes. (3) For certain λ&amp;bot; and at points, altitudes, where the ion gyroradius is equal to or less than λ&amp;bot;, the effect of wave-particle interactions is independent of the velocity and it depends only on the altitude part of the velocity diffusion coefficient; however, the effect of wave-particle interactions reduce above that point, called saturation point, and the heating process turns to be self-limiting heating. (4) The most interesting result is the appearance of O+ conics and toroids at low altitudes and continue to appear at high altitudes; however, they appear at very high altitudes for H+ ions. We compare quantitatively and qualitatively between the simulation results and the corresponding observations. As a result of many comparisons, we find that the best agreement occurs when λ&amp;bot; equals to 8 km. The quantitative comparisons show that many characteristics of the observations are very close to the simulation results, and the qualitative comparisons between the simulation results for ion outflows and the observations produce very similar behaviors. To our knowledge, most of the comparisons between observations (ion velocity distribution, density, drift velocity, parallel and perpendicular temperatures, anisotropy, etc.) and simulations obtained from different models produce few agreements and fail to explain many observations (see Yau et al., 2007; Lemaire et al., 2007; Tam et al., 2007; Su et al., 1998; Engwall et al., 2009). This paper presents many close agreements between observations and simulations obtained by Barghouthi model, for O+ and H+ ions at different altitudes i.e. from 1.7 RE to 13.7 RE.

scholarly journals Mechanisms of the electron density depletion in the SAR arc region

1996 ◽  
Vol 14 (2) ◽  
pp. 211-221 ◽  
Author(s):  
A. V. Pavlov
Keyword(s):  
Electric Field ◽  
Magnetic Storm ◽  
Electron Density ◽  
Drift Velocity ◽  
Recovery Phase ◽  
Electron Densities ◽  
Model Framework ◽  
Vibrationally Excited ◽  
Plasma Drift ◽  
Excited Nitrogen

Abstract. This study compares the measurements of electron density and temperature and the integral airglow intensity at 630 nm in the SAR arc region and slightly south of this (obtained by the Isis 2 spacecraft during the 18 December 1971 magnetic storm), with the model results obtained using the time dependent one-dimensional mathematical model of the Earth\\'s ionosphere and plasmasphere. The explicit expression in the third Enskog approximation for the electron thermal conductivity coefficient in the multicomponent mixture of ionized gases and a simplified calculation method for this coefficient presents an opportunity to calculate more exactly the electron temperature and density and 630 nm emission within SAR arc region are used in the model. Collisions between N2 and hot thermal electrons in the SAR arc region produce vibrationally excited nitrogen molecules. It appears that the loss rate of O+(4S) due to reactions with the vibrationally excited nitrogen is enough to explain electron density depression by a factor of two at F-region heights and the topside ionosphere density variations within the SAR arc if the erosion of plasma within geomagnetic field tubes, during the main phase of the geomagnetic storm and subsequent filling of geomagnetic tubes during the recovery phase, are considered. To explain the disagreement by a factor 1.5 between the observed and modeled SAR arc electron densities an additional plasma drift velocity ~–30 m s–1 in the ion continuity equations is needed during the recovery phase. This additional plasma drift velocity is likely caused by the transition from convecting to corotating flux tubes on the equatorward wall of the trough. The electron densities and temperatures and 630 nm integral intensity at the SAR arc and slightly south of this region as measured for the 18 December 1971 magnetic storm were correctly described by the model without perpendicular electric fields. Within this model framework the effect of the perpendicular electric field ~100 mv m–1 with a duration ~1 h on the SAR arc electron density profiles was found to be large. However, this effect is small if ~1–2 h have passed after the electric field was set equal to zero.

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