What is called diffusion current?
This is the current which is due to the transport of charges occurring because of non-uniform concentration of charged particles in a semiconductor. The drift current, by contrast, is due to the motion of charge carriers due to the force exerted on them by an electric field.
What is diffusion current in pn junction diode?
When a p-n junction is formed, holes diffuse from the p-side to the n-side while electrons diffuse from the n-side to the p-side. This result due to the concentration gradient across p and n sides, which gives rise to a diffusion current across the junction.
What is the difference between drift and diffusion current?
Hint: Drift current is the electric current due to the movement of charge carriers under the impact of an outer electric field, while diffusion current is the electric current due to the distribution of carriers, pointing to a change in carrier collection.
How does diffusion current work?
Generally in semiconductors, one can find the movement of charge carriers. This movement of the carriers is termed as Diffusion. The movement of carriers is observed from the higher concentration area to the lower concentration area. This type of current is referred to as Diffusion Current for the semiconductors.
What is diffusion current in pharmaceutical analysis?
[də′fyü·zhən ‚kər·ənt] (analytical chemistry) In polarography with a dropping-mercury electrode, the flow that is controled by the rate of diffusion of the active solution species across the concentration gradient produced by the removal of ions or molecule at the electrode surface.
What is the direction of diffusion current?
For example, if the derivative of p with respect to x is positive, then the concentration of holes is growing as you move towards the +x direction. Diffusion current will be the opposite of that, the holes will be diffusing in the -x direction to where there’s a lower concentration of holes.
Is diffusion or drift current greater?
These newly generated charge carrier in depletion region causes drift current to flow in opposite direction of diffusion current. Now, as only few of the diffusive charge carrier causes generation of drift charge carrier, diffusion current is less than drift current.
What is Amperometry used for?
Amperometry involves the measurements of currents at constant voltage applied at the dropping mercury electrode. The value of electrode potential is chosen in such a way that only the metal ion is reduced. This method is generally used for the determination of metal ion present in aqueous solution.
Where does the diffusion current take place in a semiconductor?
Diffusion current is mainly generated in semiconductors.The doping done in the semiconductors is non-uniform. In order to achieve uniformity, the flow of charge carriers takes place from higher concentration area to lower concentration area. It is referred to as diffusion.
When is diffusion current density high or low?
Diffusion current density is proportional to the concentration gradient. If the value of the concentration gradient is high then the density will be high. If concentration gradient value is low in that case diffusion density will also be low.
How is the rate of diffusion in solar cells measured?
The rate at which diffusion occurs depends on the velocity at which carriers move and on the distance between scattering events. It is termed diffusivity and measured in cm 2 s -1. Values for silicon, the most used semiconductor material for solar cells, are given in the appendix.
What are some of the effects of diffusion?
One major effect of diffusion is that, with time, it evens out the carrier concentrations in a device, such as those induced by generation and recombination, without an external force being applied to the device.