BE Civil Engineering Semester 1 (FE First Year)University of Mumbai
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# Define drift current, diffusion current and P-N junction. The electrical conductivity of a pure silicon at room temperature is 4×10-4 mho/m . - BE Civil Engineering Semester 1 (FE First Year) - Applied Physics 1

ConceptConductivity, mobility, current density (drift & diffusion) in semiconductors(n type and p type)

#### Question

Define drift current, diffusion current and P-N junction. The electrical conductivity of a pure silicon at room temperature is 4×10-4 mho/m . if the mobility of electron is 0.14m2 /V-S and that of hole is 0.04m2 /V-S. calculate the intrinsic
carrier density.

#### Solution

DRIFT CURRENT :-
Drift current is the electric current, or movement of charge carriers, which is due to the applied electric field, often stated as the electromotive force over a given distance.

DIFFUSION CURRENT:-
Diffusion current is a current in a semiconductor caused by the diffusion of charge carriers. This is the current which is due to the transport of charges occurring because of nonuniform concentration of charged particles in a semiconductor.

⦁ P-N JUNCTION:-
A diode is a PN junction with p-type on one side and n-type on the other. When a positive voltage is applied to the p-type side , it shrinks and overcomes the depletion zone, causing the current flow from the p-type to the n-type side.

NUMERICAL:-
Given Data :- σ = 4×10-4mho/m , μe = 0.14m2/V-sec , μh= 0.04m2/V-S

Formula :- σi = nie + μh ).e

Calculations :- ni = (σi)/ ((μ_e + μ_h ).e)
=( 4×10^-4)/(1.6×10^(-19)(0.14+0.040)

n_i = 1.388 ×10^16/m^3`
Answer :- carrier concentration = 1.388 ×1016 /m

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#### APPEARS IN

Solution Define drift current, diffusion current and P-N junction. The electrical conductivity of a pure silicon at room temperature is 4×10-4 mho/m . Concept: Conductivity, mobility, current density (drift & diffusion) in semiconductors(n type and p type).
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