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प्रश्न
The number of silicon atoms per m3 is 5 × 1028. This is doped simultaneously with 5 × 1022 atoms per m3 of Arsenic and 5 × 1020 per m3 atoms of Indium. Calculate the number of electrons and holes. Given that ni= 1.5 × 1016 m−3. Is the material n-type or p-type?
उत्तर
Number of silicon atoms, N = 5 × 1028 atoms/m3
Number of arsenic atoms, nAs = 5 × 1022 atoms/m3
Number of indium atoms, nIn = 5 × 1020 atoms/m3
Number of thermally-generated electrons, ni = 1.5 × 1016 electrons/m3
Number of electrons, ne = 5 × 1022 − 1.5 × 1016 ≈ 4.99 × 1022
Number of holes = nh
In thermal equilibrium, the concentrations of electrons and holes in a semiconductor are related as:
nenh = ni2
`therefore "n"_"h" = ("n"_"i"^2)/"n"_"e"`
`= (1.5 xx 10^16)^2/(4.99 xx 10^22) ~~ 4.51 xx 10^9`
Therefore, the number of electrons is approximately 4.99 × 1022 and the number of holes is about 4.51 × 109. Since the number of electrons is more than the number of holes, the material is an n-type semiconductor.
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संबंधित प्रश्न
In a p-type semiconductos, which of the following statement is true:
Distinguish between intrinsic and extrinsic semiconductor. (Give any two points).
A donor impurity results in ______.
Semiconductors formed by doping germanium (Ge) with aluminium (Z = 13) and antimony (Z = 51) are ______.
When p-n junction diode is forward biased, then ______.
In n-type semiconductor majority carriers and minority carriers are respectively ______.
In p-type semiconductor, ______.
The electron and hole concentration in a semiconductor in thermal equilibrium is given by ______.
State how a p-type semiconductor will be obtained from a pure crystal of a semiconductor.
Explain the following term:
Extrinsic semiconductor
Distinguish between n-type and p-type semiconductors.
The conductivity of a semiconductor increases with increase in temperature because ______.
Why are elemental dopants for Silicon or Germanium usually chosen from group XIII or group XV?
Sn, C, and Si, Ge are all group XIV elements. Yet, Sn is a conductor, C is an insulator while Si and Ge are semiconductors. Why?
Two crystals C1 and C2, made of pure silicon, are doped with arsenic and aluminium respectively.
Identify the extrinsic semiconductors so formed.
- Statement I: By doping silicon semiconductor with pentavalent material, the electrons density increases.
- Statement II: The n-type semiconductor has net negative charge. In the light of the above statements, choose the most appropriate answer from the options given below:
Pieces of copper and of silicon are initially at room temperature. Both are heated to temperature T. The conductivity of ______.
- Assertion (A): Putting the p-type semiconductor slab directly in physical contact with the n-type semiconductor slab cannot form the pn junction.
- Reason (R): The roughness at contact will be much more than inter atomic crystal spacing and continuous flow of charge carriers is not possible.
