The diffusion current density can be calculated by equation 1. … n1 = (1.5 · 1010) cm−3)2 1017cm−3 = 2.25 · 103cm−3 1 Page 2 Because the doping varies linearly the derivation of p and n can be evaluated by equation 1.3 and 1.4.
Table of Contents
What is the expression of the diffusion current?
Diffusion current = the movement caused by variation in the carrier concentration. Drift current = the movement caused by electric fields. Direction of the diffusion current depends on the slope of the carrier concentration. Direction of the drift current is always in the direction of the electric field.
What is mobility formula?
Mobility μ is defined as the magnitude of drift velocity per unit electric field. μ=E∣vd∣. Its SI unit is m2/Vs.
How drift current differ from 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.
Which equation is used for measuring diffusion current Mcq?
What is diffusion current in pn junction?
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 diffusion electron?
The process by which, charge carriers (electrons or holes) in a semiconductor moves from a region of higher concentration to a region of lower concentration is called diffusion. … The electrons present at left side of the semiconductor material will moves to right side, to reach the uniform concentration of electrons.
What is the direction of diffusion current?
The direction of diffusion current is that where positively charged particles move.
What is diffusion current in analytical chemistry?
[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 mobility in electric current?
Mobility is formally defined as the value of the drift velocity per unit of electric field strength; thus, the faster the particle moves at a given electric field strength, the larger the mobility.
How do you find electron mobility?
When this is not true (for example, in very large electric fields), mobility depends on the electric field. The SI unit of velocity is m/s, and the SI unit of electric field is V/m. Therefore the SI unit of mobility is (m/s)/(V/m) = m2/(V⋅s).
How do you find electron and hole mobility?
Electron and hole mobility
- The ability of an electron to move through a metal or semiconductor, in the presence of applied electric field is called electron mobility.
- Vn = µnE.
How do you calculate drift current?
What is Drift Current?
- Derivation: The flow of charge carriers in response to the electric field is known as drift current. This concept is frequently used in the electrons & holes context in the semiconductor. …
- Vn = µnE. …
- Vp = µpE. …
- Jn= enµnE. …
- Jp= epµpE. …
- J = Jn + Jp. …
- = enµnE + epµpE.
- J = eE(nµn + pµp)
What is diffusion and drift in pn junction?
Diffusion and drift Diffusion is the process of movement of charge carriers due to concentration gradient along the semiconductor. In a p-n junction, n-side has excess of electrons and hence electrons diffuse from n-side to p-side. … Drift is the process of movement of charge carriers due to the net electric field.
What is diffusion current and drift current in pn junction diode?
The current caused by the diffusion of carriers across the junction is called a diffusion current. … Minority carriers which reach the edge of the diffusion region are swept across it by the electric field in the depletion region. This current is called the drift current.
What does DN DX represents?
Explanation: dn/dx represent velocity gradient.
How does diffusion current produce the depletion region *?
Explanation: The diffusion of carriers from one side to another makes the holes and electrons to collect on either side of the junction creating the depletion region.
What is polarography Maxima?
Maxima, frequently observed on polarographic waves due to the reduction or oxidation of cations, anions or neutral molecules thus interferring with analyte quantification, are usually suppressed by the addition of minute amounts of an appropriate surfacc-active agent.
What is the direction of diffusion current in a pn junction diode?
from the n-side to the p-side if the junction is forward-biased and in the opposite direction if it is reverse-biased.
What is drift and diffusion current in diodes answer?
Drift current is electric current due to the motion of charge carriers under the influence of an external electric field while diffusion current is electric current due to the diffusion of carriers leading to a change in carrier concentration.
What is the direction of diffusion current in the function diode?
from the p-side to the n-side if the junction is forward-biased and in the opposite direction if it is reverse-biased.
What is Fick’s Law of diffusion equation?
Fick’s First Law Movement of solute from higher concentration to lower concentration across a concentration gradient. J=−Ddφdx. Where,J: diffusion flux. D: diffusivity.
What is carrier diffusion?
Diffusion is the random scattering of carriers to produce a uniform distribution. p> 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 cm2s– 1.
Why is diffusion current negative in holes?
The concentration of holes is decreasing as you go from the -x to +x direction. Therefore, holes will diffuse to the +x direction where there’s a lower concentration of holes. This is why the negative sign is needed in the equation for the hole diffusion current.
What is drift in pn junction?
Drift current in a p-n junction diode In a p-n junction diode, electrons and holes are the minority charge carriers in the p-region and the n-region, respectively. … In a biased p-n junction, the drift current is independent of the biasing, as the number of minority carriers is independent of the biasing voltages.
What determines direction of diffusion?
What determines the direction of diffusion? The relative concentration of the substance in different areas determines the direction of diffusion. Diffusion occurs from regions of high concentration to regions of low concentration.
What is polarography write Ilkovic equation and its use?
A relation used in polarography relating the diffusion current i a and the concentration c. The Ilkovic equation has the form i a=kc, where k is a constant.
What are the factors that affect the diffusion current?
Several factors affect the rate of diffusion of a solute including the mass of the solute, the temperature of the environment, the solvent density, and the distance traveled.
Is used as Maxima suppressor in polarography?
Agar is shown to be an effective suppressor of maxima and a suffiClent amount can dissol ve in a short.