Search results
Results from the WOW.Com Content Network
Diffusion current is a current in a semiconductor caused by the diffusion of charge carriers (electrons and/or electron holes). This is the current which is due to the transport of charges occurring because of non-uniform concentration of charged particles in a semiconductor.
This process generates current, referred to as diffusion current. Diffusion current can also be described by Fick's first law = /, where J is the diffusion current density (amount of substance) per unit area per unit time, n (for ideal mixtures) is the electron density, x is the position [length].
The drift velocity, and resulting current, is characterized by the mobility; for details, see electron mobility (for solids) or electrical mobility (for a more general discussion). See drift–diffusion equation for the way that the drift current, diffusion current, and carrier generation and recombination are combined into a single equation.
This diffusion current is governed by Fick's law: = where: F is flux. D e is the diffusion coefficient or diffusivity; is the concentration gradient of electrons; The diffusion coefficient for a charge carrier is related to its mobility by the Einstein relation.
D is the diffusion coefficient for species in cm 2 /s; t is the time in seconds. Under controlled-diffusion circumstances, the current-time plot reflects the concentration gradient of the solution near the electrode surface. The current is directly proportional to the concentration at the electrode surface.
In semiconductor physics, the Haynes–Shockley experiment was an experiment that demonstrated that diffusion of minority carriers in a semiconductor could result in a current. The experiment was reported in a short paper by Haynes and Shockley in 1948, [1] with a more detailed version published by Shockley, Pearson, and Haynes in 1949.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
On the other hand, majority carriers are driven into the drift region by diffusion (resulting from the concentration gradient), which leads to the forward current; only the majority carriers with the highest energies (in the so-called Boltzmann tail; cf. Maxwell–Boltzmann statistics) can fully cross the drift region. Therefore, the carrier ...