scholarly journals Generalized Einstein Relation and Negative Differential Conductivity in Gases

1984 ◽  
Vol 37 (1) ◽  
pp. 35 ◽  
Author(s):  
RE Robson
Keyword(s):  
Electric Field ◽  
Momentum Transfer ◽  
Applied Electric Field ◽  
Transport Coefficients ◽  
Charged Particles ◽  
Inelastic Collisions ◽  
Einstein Relation ◽  
Negative Differential Conductivity ◽  
Differential Conductivity ◽  
Generalized Einstein Relation

Transport coefficients of charged particles undergoing both elastic and inelastic collisions with a gas of neutral molecules are calculated using momentum-transfer theory. A criterion is obtained for the phenomenon of negative differential conductivity (i.e. the drift velocity decreasing with applied electric field) and the well-known generalized Einstein relation is appropriately modified.

BALLISTIC ELECTRON ACCELERATION NEGATIVE-DIFFERENTIAL-CONDUCTIVITY DEVICES

2007 ◽  
Vol 17 (01) ◽  
pp. 173-176 ◽  
Author(s):  
BARBAROS ASLAN ◽  
LESTER F. EASTMAN ◽  
WILLIAM J. SCHAFF ◽  
XIAODONG CHEN ◽  
MICHAEL G. SPENCER ◽  
...  
Keyword(s):  
Experimental Data ◽  
Electric Field ◽  
Electron Acceleration ◽  
Negative Differential Conductivity ◽  
Differential Conductivity ◽  
Experimental Development ◽  
Ballistic Electron

We present the experimental development and characterization of GaN ballistic diodes for THz operation. Fabricated devices have been described and gathered experimental data is discussed. The major problem addressed is the domination of the parasitic resistances which significantly reduce the accelerating electric field across the ballistic region (intrinsic layer).

BALLISTIC ELECTRON ACCELERATION NEGATIVE-DIFFERENTIAL-CONDUCTIVITY DEVICES

2006 ◽  
Vol 16 (02) ◽  
pp. 437-441
Author(s):  
Lester F. Eastman ◽  
William J. Schaff ◽  
Ho-Young Cha ◽  
Xiao-Dong Chen ◽  
Michael G. Spencer ◽  
...  
Keyword(s):  
Electric Field ◽  
Electron Acceleration ◽  
Finite Energy ◽  
High Electric Field ◽  
Negative Differential Conductivity ◽  
Differential Conductivity ◽  
Ballistic Electron ◽  
Drift Conditions ◽  
On Chip

A short drift distance N - I - N device, with high electric field, allows ballistic electron accelerations and drift. Conditions can be enhanced by using a heterojunction to launch electrons at finite energy. Initial I(V) results without the heterojunctions are presented, as well as the design of a structure which has the heterostructure, projected results are speculated upon, along with an on-chip circuit being used.

scholarly journals Charged Particle Transport in Gaseous Nitrogen at Intermediate E/N using the Voltage Transient Method

1992 ◽  
Vol 45 (1) ◽  
pp. 75 ◽  
Author(s):  
PH Purdie ◽  
J Fletcher
Keyword(s):  
Electric Field ◽  
Applied Electric Field ◽  
Charged Particles ◽  
Transport Parameters ◽  
Ion Diffusion ◽  
Electrode Gap ◽  
Nitrogen Gas ◽  
Voltage Transient ◽  
Charged Particle Transport ◽  
And Diffusion

A pulsed swarm of charged particles crossing an inter-electrode gap under the influence of an applied electric field E will produce a pulsed current in the external circuit which, when integrated over time, will result in a transient voltage pulse, the shape and magnitude of which is characteristic of the number and type of charged particles. This voltage transient technique has been used to investigate a gas discharge in nitrogen gas at values of EIN (the ratio of applied electric field to gas number density), such that ionisation is non-negligible. The voltage transients have been subjected to a theoretical analysis, which has previously been reported, which includes not only cathode and anode image terms but also both electron and ion diffusion terms. Electron transport parameters are reported for EIN ::; 350 Td (1 Td = 10-17 V cm2). Data are also obtained for the drift velocities and diffusion coefficients of the ions operative within the nitrogen discharge. An estimate is obtained for the collisional decay rate of Nt.

scholarly journals Approximate Formulas for Ion and Electron Transport Coefficients in Crossed Electric and Magnetic Fields

1994 ◽  
Vol 47 (3) ◽  
pp. 279 ◽  
Author(s):  
RE Robson
Keyword(s):  
Magnetic Fields ◽  
Transport Coefficients ◽  
Anisotropic Scattering ◽  
Negative Differential Conductivity ◽  
Differential Conductivity ◽  
Electric And Magnetic Fields ◽  
Electrons And Ions ◽  
Approximate Expressions ◽  
Electron Transport Coefficients ◽  
The Magnetic Field

Momentum-transfer theory is used to derive approximate expressions for transport properties of electrons and ions in a gas in crossed electric and magnetic fields. Included in the formal discussion are the generalised Einstein relations, negative differential conductivity, Tonks' theorem and the equivalent reduced electric field concept. Specific topics dealt with include the ratio D II / D1. for electrons, which 'flips over' as the magnetic field is increased, the enhancement of negative differential conductivity through increased BIN, and a discussion of anisotropic scattering.

Magnetic Stirring During Electrolytic Thinning

1969 ◽  
Vol 27 ◽  
pp. 144-145
Author(s):  
J. Dash ◽  
R.W. Roeter ◽  
W.W. King
Keyword(s):  
Electric Field ◽  
Applied Electric Field ◽  
Charged Particles ◽  
Metal Foil ◽  
Gas Evolution ◽  
Combined Effects ◽  
Anode Layer ◽  
Gravitational Fields ◽  
Magnetic Stirring ◽  
Ionic Nature

The profile of an electrolytically-thinned metal foil is largely determined by the combined effects of electric and gravitational fields. Uniform thinning can be approached by making the applied electric field as uniform as possible and by utilizing some kind of stirring to counteract the variation in viscous anode layer thickness caused by gravity. Gas evolution at the sample may also play an important role in the process. Because of the ionic nature of electrolysis, it might be expected that applied magnetic fields of appreciable strength should produce significant changes in the process due to the Lorentz force on charged particles. Preliminary experiments have shown that this is the case. The net effect of these changes in the experiments thus far has been to enhance the uniformity of thinning.

scholarly journals Model Calculations of Negative Differential Conductivity in Gases

1984 ◽  
Vol 37 (1) ◽  
pp. 23 ◽  
Author(s):  
ZLj Petrovic ◽  
RW Crompton ◽  
GN Haddad
Keyword(s):  
Momentum Transfer ◽  
Cross Section ◽  
Electron Scattering ◽  
Cross Sections ◽  
Inelastic Collision ◽  
Negative Differential Conductivity ◽  
Differential Conductivity ◽  
Model Calculations ◽  
Momentum Transfer Cross Section ◽  
Simple Models

Negative differential conductivity in gases has been studied using simple models of elastic and inelastic collision cross sections for electron scattering. The use of such models has demonstrated features of the cross sections that lead to the phenomenon, and shown that it can occur without a Ramsauer–Townsend minimum (and even without a sharply rising momentum-transfer cross section) or a special combination of inelastic cross sections.

scholarly journals A Note on the Longitudinal Diffusion of Electrons in Argon

1972 ◽  
Vol 25 (5) ◽  
pp. 637 ◽  
Author(s):  
AG Robertson ◽  
JA Rees
Keyword(s):  
Electric Field ◽  
Momentum Transfer ◽  
Cross Section ◽  
Diffusion Coefficients ◽  
Applied Electric Field ◽  
Longitudinal Diffusion ◽  
Marked Influence ◽  
Momentum Transfer Cross Section

It has been shown both experimentally and theoretically that the diffusion of electrons subject to the influence of an applied electric field is often significantly different in directions parallel and normal to the electric field (Wagner, Davis, and Hurst 1967; Parker and Lowke 1969; Lowke and Parker 1969; Skullerud 1969). Lowke and Parker (1969) showed that the ratio of the diffusion coefficients (DL parallel to the electric field and DT normal to the field) is particularly sensitive to rapid variations with energy of the momentum transfer cross section of the electrons. It is to be expected therefore that for electrons in argon the Ramsauer?Townsend minimum in the momentum transfer cross section at energies of ~ 0�3 eV will have a marked influence on the value of DL.

scholarly journals Generation of sequences of strong electric monopulses in nitride films

2021 ◽  
Vol 34 (2) ◽  
pp. 187-201
Author(s):  
Volodymyr Grimalsky ◽  
Svetlana Koshevaya ◽  
Jesus Escobedo-Alatorre ◽  
Anatoliy Kotsarenko
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Strong Electric Field ◽  
Numerical Algorithms ◽  
Negative Differential Conductivity ◽  
Differential Conductivity ◽  
Threshold Values ◽  
Bias Electric Field ◽  
Bulk Semiconductors ◽  
Strong Electric Fields

This paper presents theoretical investigation of the excitation of the sequences of strong nonlinear monopulses of space charge waves from input small envelope pulses with microwave carrier frequencies due to the negative differential conductivity in n-GaN and n-InN films. The stable numerical algorithms have been used for nonlinear 3D simulations. The sequences of the monopulses of the strong electric field of 3 - 10 ps durations each can be excited. The bias electric field should be chosen slightly higher than the threshold values for observing the negative differential conductivity. The doping levels should be moderate 1016 -1017 cm-3in the films of ? 2 mm thicknesses. The input microwave carrier frequencies of the exciting pulses of small amplitudes are up to 30 GHz in n-GaN films, whereas in n-InN films they are lower, up to 20 GHz. The sequences of the electric monopulses of high peak values are excited both in the uniform nitride films and in films with non-uniform conductivity. These nonlinear monopulses in the films differ from the domains of strong electric fields in the bulk semiconductors. In the films with non-uniform doping the nonlinear pulses are excited due to the inhomogeneity of the electric field near the input end of the film and the output nonlinear pulses are rather domains.

Sign in / Sign up

Export Citation Format

Share Document