Semiconductors GaN, AlGaN -- Questions about abbreviations

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Discussion Overview

The discussion revolves around the meanings of various chemical abbreviations related to semiconductors, specifically GaN (Gallium Nitride) and its alloys, including AlGaN and AlN. Participants seek clarification on the significance of certain notations, concentrations, and stoichiometry in the context of semiconductor materials.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the meaning of "u" in u-GaN, suggesting it might refer to undoped GaN, and seeks clarification on the concentration of atoms per cm3.
  • Another participant asserts that "C" before GaN indicates carbon concentration, specifically in the context of u-GaN and C:GaN.
  • There is a discussion about the meaning of the 0.1 in Al0.1GaN, with one participant stating it indicates aluminum as a dopant at up to 10 at%.
  • Participants explore the stoichiometry of Al0.3Ga0.7N, with one suggesting it means 30% aluminum and 70% gallium, while questioning the nitrogen content.
  • One participant expresses confusion about the presence of carbon in undoped u-GaN, questioning whether it implies residual carbon is present even in clean GaN.
  • Another participant revises their earlier assumption, suggesting that the concentration C:2E16 at/cm3 might refer to carrier concentration rather than atomic dopant concentration, while noting the confusion caused by the units used.
  • Some participants mention that the numbers provided are parameters of layers in semiconductor fabrication, with a note on the typical ranges for atomic dopant and carrier concentrations.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of the concentrations and the meaning of certain abbreviations, indicating that multiple competing interpretations exist without a clear consensus.

Contextual Notes

There are unresolved questions regarding the definitions of concentrations and the implications of the units used (at/cm3 vs. cm-3), as well as the presence of carbon in undoped materials.

Who May Find This Useful

This discussion may be useful for individuals studying semiconductor physics, materials science, or those involved in semiconductor fabrication and characterization.

Deleted member 655103
Hi, I have some chemical abbreviation which I do not understand. Please can you tell me what those abbreviations mean?

1. u-GaN 800nm (C:2E16 at/cm3) (I do not understand what "u" stands for; GaN is Gallium Nitride, 800 nm is thickness of layer, C is concentration of atoms per cm3 but I am not sure concentration of what?)

2. C:GaN 700nm (C:2E19 at/cm3) (what is C before GaN and again concentration 2E19 at/cm3 of what?)

3. AlN/Al0.1GaN 5/25 nm (I do not know what 0.1 in Al0.1GaN means; I know that 5nm is Alluminiu Nitride, 25nm Alluminium Gallium Nitride)

4. Al0.3Ga0.7N (what means 0.3 and 0.7? I think it means that 30% of Al and 70% of Ga, but what about N (nitrogen)? is it 50% of Nitrogen and from remaining 50% is 30%Al and 70% of Ga so over all 50%N, 15%Al, 35%Ga? Am I wrong?

Thanks for answers!
 
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epsilonpi said:
u-GaN 800nm (C:2E16 at/cm3) (I do not understand what "u" stands for; GaN is Gallium Nitride, 800 nm is thickness of layer, C is concentration of atoms per cm3 but I am not sure concentration of what?)
"u" means undoped. The C:2E16 is the concentration of carbon atoms in the gallium nitride.
epsilonpi said:
2. C:GaN 700nm (C:2E19 at/cm3) (what is C before GaN and again concentration 2E19 at/cm3 of what?)
Again, C is carbon here.
epsilonpi said:
AlN/Al0.1GaN 5/25 nm (I do not know what 0.1 in Al0.1GaN means; I know that 5nm is Alluminiu Nitride, 25nm Alluminium Gallium Nitride)
This means that aluminum is a dopant in GaN at up to 10 at%.
epsilonpi said:
Al0.3Ga0.7N (what means 0.3 and 0.7? I think it means that 30% of Al and 70% of Ga, but what about N (nitrogen)? is it 50% of Nitrogen and from remaining 50% is 30%Al and 70% of Ga so over all 50%N, 15%Al, 35%Ga? Am I wrong?
Thanks for answers!
This is just basic stoichiometry, but presented in a way that may not be familiar from intro chemistry classes (the convention is, however, standard in solid state chemistry and physics). Pure GaN has one gallium atom for every nitrogen atom. Al0.3Ga0.7N has 0.3 aluminum atoms and 0.7 gallium atoms for every nitrogen, so in terms of atom percent, it's 50% N,15% Al, 35% Ga.
 
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Thank you for your answer.
I am little bit confused why do we have concentration of Carbon in undoped u-GaN? There should be no Carbon or does it mean that even if it is clean GaN there is still some carbon present but we did not add it into GaN by purpose?
 
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Actually, I think I was wrong. I assume that the C:2E16 at/cm3 refers to the carrier concentration: so undoped GaN has no carbon in it, but the carrier concentration in this case would be 2E16 cm-3. What's throwing me off is the units of at/cm3, which implies an atomic dopant concentration, instead of a carrier concentration. Where are these numbers coming from?
 
Those numbers are parameters of layers in semiconductor parts. This is how they were fabricated. Thanks for your help.
 
epsilonpi said:
Those numbers are parameters of layers in semiconductor parts. This is how they were fabricated. Thanks for your help.
NB--The range of numbers (1016-1019) suggests an atomic dopant as well. Carrier concentrations tend to be 1012-1015 cm-3. You might check the supplier's data sheet on the semiconductor if you have it.
 
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