Semiconductor Doping: Does Impurity Type Matter?

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    Doping Semiconductor
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Discussion Overview

The discussion revolves around the impact of different types of impurities used in doping semiconductors, specifically whether the type of dopant (from group 3 or 5) affects activation voltage or if it is solely dependent on the level of doping. Participants explore the properties of silicon semiconductors doped with phosphorus versus arsenic at varying concentrations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions if the type of impurity matters in terms of activation voltage, suggesting that silicon doped with phosphorus and arsenic at similar concentrations might exhibit the same properties.
  • Another participant, while not a specialist, asserts that the classical model of semiconductors does not differentiate between specific n-type dopants if they contribute the same number of conduction electrons/holes.
  • This participant notes that while different elements may have varying electron densities leading to minimal effects, these nuances are often not captured in simpler models of extrinsic semiconductivity.
  • A later reply clarifies that while dopants may be distinct in terms of the type of charge carriers they contribute (e.g., boron versus aluminum), the carriers themselves (electrons/holes) are treated as non-distinct in classical models.

Areas of Agreement / Disagreement

Participants express differing views on whether the type of dopant affects semiconductor properties, with some suggesting minimal differences while others highlight potential distinctions based on dopant characteristics. The discussion remains unresolved regarding the significance of these differences.

Contextual Notes

Participants acknowledge that assumptions about the number of conduction electrons/holes contributed by different dopants may influence the discussion. There is also a recognition that the classical model may not encompass all complexities of semiconductor behavior.

phjw
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Hi just a quick question, does the type of impurity (as long as its from group 3 or 5 respectively) used in doping a semiconductor matter in terms of its activation voltage or is it just down to the level of doping?

So for instance a would say a silicon semiconductor doped with 1 to 10,000 parts phosphorus, have exactly the same properties as if it was doped with 1 to 10,000 parts arsenic?

Thanks ozzie
 
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Anyone? surly it has an easy answer?
 
To the best of my knowledge (and I'm not a specialist in the field, mind), the classical model of semi-conductors makes no distinction between the specific dopants, provided they're both of either p- or n-type. Thus, two n-type dopants, when added in the same amount, would produce indistinguishable effects.

Note: This assumes, of course, that the dopants contribute the same number of electrons/holes. X number of atoms of this may contribute fewer conduction electrons than X number of this atom; so I'll assume by "parts" that you mean the same number of contributed electrons/holes, not the same number of atoms.

you can appreciate that there are no "absolute truths." I'm sure that as different elements have different electron densities, there will be different effects, but these are only minimal and are not included in the more simple, standard model of extrinsic semi-conductivity. (It would be an interesting problem from the perspective of density-functional theory.)

I wouldn't stake my life or my pension on this answer, but it is logically consistent. I hope this helps!
 
** To correct myself in the first sentence of that last post-- classical sources regarding doped superconductors make no distinction between ELECTRONS/HOLES. Dopants are distinct. Boron and aluminum contribute different holes, but the holes themselves are non-distinct... Semantics, I know.
 

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