Determining Charge Carrier Concentration from Doping in Si Crystal

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Discussion Overview

The discussion revolves around determining the type of charge carriers in a silicon crystal doped with antimony and boron, specifically focusing on whether the crystal is type p or type n, and calculating the concentrations of minority and majority charge carriers. The scope includes theoretical considerations of semiconductor doping and charge carrier dynamics.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • Some participants propose that the silicon crystal is type p due to the higher concentration of boron (acceptor) atoms compared to antimony (donor) atoms.
  • One participant calculates the majority charge carriers to be 10^16 cm^-3 based on the concentration of boron.
  • Another participant questions how the majority charge carrier concentration of 10^16 cm^-3 was derived.
  • Participants discuss the definitions of n0, p0, and ni, with one explaining that n0 is the thermal equilibrium density of electrons, p0 is the thermal equilibrium density of holes, and ni is the electron density in intrinsic semiconductors.
  • There is a formula presented (Npo=ni^2/p0) for calculating the minority carrier density, with a specific calculation yielding a minority carrier concentration of 10^4 cm^-3.

Areas of Agreement / Disagreement

Participants generally agree that the silicon crystal is type p due to the doping concentrations, but there is some uncertainty regarding the calculations of charge carrier concentrations and the definitions of terms used in the discussion.

Contextual Notes

Some assumptions regarding intrinsic carrier concentration (ni) and the specific values used in calculations are not explicitly stated, which may affect the interpretations of the results.

nhrock3
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a silicon crystal is doped with 10^15 cm^-3 atoms of antimony
and its also doped with 10^16 cm^-3 atoms of boron

will the crystal be type p or type n

what will be the concentration of minory charge carriers and majority charge carriers
?

Boron has 3 electrons in outer circle
and Sb has 5 on the outer circle
so its type "p" because there there is more +3 then +5
thats as far as could go
how to find the concentration of minory charge carriers and majority charge carriers
 
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nhrock3 said:
a silicon crystal is doped with 10^15 cm^-3 atoms of antimony
and its also doped with 10^16 cm^-3 atoms of boron

will the crystal be type p or type n

what will be the concentration of minory charge carriers and majority charge carriers
?

Boron has 3 electrons in outer circle
and Sb has 5 on the outer circle
so its type "p" because there there is more +3 then +5
thats as far as could go
how to find the concentration of minory charge carriers and majority charge carriers

But the two doping densities are not the same...
 
boron is an acceptor donates 1 hole per atom.
Sb is a donor, donates 1 electon per atom

10^16 boron atoms vs 10^15 Sb means that this is a P type.

n0p0=ni^2

minority negative charge carriers : Npo=ni^2/p0 = 10^20/10^16 = 10^4 cm^-3

major charge carriers = 10^16
 
what are n0 p0 and ni
?

what N represents in Npo=ni^2/p0 ?
 
n0 is thermal equibrium density of electrons
p0 is thermal equilibruim density of holes

ni = electron density in intrinsic semiconductor

Npo is the thermal equilibrium minority carrier density.
 
how you get that the "major charge carriers = 10^16 "
?
 

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