Negative differential conductivity

Negative differential conductivity

Negative differential conductivity (NDC) is a nonlinear electrical phenomenon. If J is not a monotonic function of E at some values of E, the conductivity will be negative: \sigma=\frac{dJ}{dE}<0and negative differential conductivity is experienced; that is, in some electric field, as the current density increases, the electric field strength is decreased. In practice, one observes that the voltage drop across the "device under test" decreases when the current is increased.

Negative differential conductivity has been observed experimentally in some semiconductors (tunnel diodes, thyristors, and like structures). As well, non-equibrium plasma shows this behaviour. Even a simple gas-filled tube from a fluorescent lamp does.

The physical mechanisms that result in such effect are different, but they can be understood generally under processes such as impact ionisation.

Types

Different shapes of the J versus E function exist, which according to the shape, S, N, and Z-type materials can be categorised. In the S-type or S-shaped negative differential conductivity (SNDC) in a range of electric field, the current density is a multi-valued function of the electric field but the electric field is a single-valued function of current density and can be calculated withouth ambiguity from the value of the current density. A current filaments— an inhomogeneity in the current density distribution lateral to the direction of the current flow (orthogonal to the current density vector)—is common in devices showing current-type negative differential conductivity, especially of S-types. A Thyristor is a good example of an SNDC device.

References


Wikimedia Foundation. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • NDC — or ndc may refer to: IATA code for Nanded Airport, India ndc, name daemon control program in some Unix based BIND name server environments N.D.C., a 2002 single by Australian band Jebediah National Defence Commission of North Korea National… …   Wikipedia

  • Leo Esaki — Infobox Scientist name =Leo Esaki imagesize = 180px caption =Leo Esaki birth date =March 12, 1925 (age 83) birth place = Osaka, Japan nationality = Japan field = work institutions = alma mater = doctoral advisor = doctoral students = known for… …   Wikipedia

  • Current filament — A current filament is an inhomogeneity in the current density distribution lateral to the of the current flow (that is, orthogonal to the current density vector). It is common in the devices showing current type negative differential conductivity …   Wikipedia

  • объёмная дифференциальная отрицательная проводимость — — [Я.Н.Лугинский, М.С.Фези Жилинская, Ю.С.Кабиров. Англо русский словарь по электротехнике и электроэнергетике, Москва, 1999] Тематики электротехника, основные понятия EN bulk negative differential conductivity …   Справочник технического переводчика

  • NDC — biomed. abbr. National Drug Code comp. abbr. National Data Communication non cryst. solid abbr. Negative Differential Conductivity abbr. National Destination Code (MS ISDN, GSM, Mobile Systems) abbr. Network Data Collection abbr. Node Data… …   United dictionary of abbreviations and acronyms

  • Conductive polymer — This article is about bulk applications of conductive polymers. For single molecule electronics, see Molecular scale electronics. Chemical structures of some conductive polymers. From top left clockwise: polyacetylene; polyphenylene vinylene;… …   Wikipedia

  • John McGinness — John Edward McGinness, PhD, MD, Pioneer in Organic electronics and Nanotechnology. B.S. Physics University of Houston, 1966, PhD, Physics, Rice University, 1970, MD, University of Texas Medical School at Houston, 1985. Author of roughly 40… …   Wikipedia

  • Electron mobility — This article is about the mobility for electrons and holes in metals and semiconductors. For the general concept, see Electrical mobility. In solid state physics, the electron mobility characterizes how quickly an electron can move through a… …   Wikipedia

  • Gunn diode — A Gunn diode, also known as a transferred electron device (TED), is a form of diode used in high frequency electronics. It is somewhat unusual in that it consists only of N doped semiconductor material, whereas most diodes consist of both P and N …   Wikipedia

  • Organic semiconductor — STM image of self assembled supramolecular chains of the organic semiconductor Quinacridone on Graphite. An organic semiconductor is an organic material with semiconductor properties. Single molecules, short chain (oligomers) and organic polymers …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”