Location of donor atom electrons in N-type Silicon

Click For Summary

Discussion Overview

The discussion revolves around the location of donor atom electrons in N-type silicon and the implications for energy band diagrams in solid state electronics. Participants explore the concept of the "forbidden gap" and how doping alters the energy levels within this gap.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about the energy band diagrams, particularly regarding the placement of donor electrons in relation to the forbidden gap.
  • Another participant asserts that the states in the bandgap are produced by doping atoms, indicating that undoped semiconductors do not have such states.
  • A follow-up comment questions whether the donor electrons should be located in the valence band instead of the forbidden gap.
  • Another participant clarifies that the statement about the forbidden gap applies only to undoped semiconductors and does not account for the modifications introduced by doping.

Areas of Agreement / Disagreement

Participants appear to have differing views on the implications of doping on the energy band structure, particularly regarding the presence of states in the forbidden gap. The discussion remains unresolved as participants explore these concepts.

Contextual Notes

There are limitations in the understanding of how doping affects the energy levels, and the discussion highlights the need for clarity on the definitions of terms like "forbidden gap" in the context of doped versus undoped semiconductors.

CoolDude420
Messages
199
Reaction score
9
I'm taking a module in solid state electronics and I'm a bit confused with the energy band diagrams. I was told that the region between the top of VB and and the bottom of the CB is the "forbidden gap". However after learning about N-type semiconductors(silicon), I see that the extra electron from the donor atoms have their own energy level right below the bottom of the conduction band in the so called "forbidden gap". How can this be? I'm quite new to solid state and all of its terminology so any help is appreciated.

Heres a pic: [cant post pic]. its the first one on this page
http://hyperphysics.phy-astr.gsu.edu/hbase/solids/dsem.html#c2

dban2.gif
 
Physics news on Phys.org
The states are produced by the doping atoms. Undoped semiconductors don't have states in the bandgap, but doped semiconductors do.
 
mfb said:
The states are produced by the doping atoms. Undoped semiconductors don't have states in the bandgap, but doped semiconductors do.

Shouldn't they be in the VB though? Since nothing is meant to be in the Forbidden Gap
 
CoolDude420 said:
Since nothing is meant to be in the Forbidden Gap
This statement applies to electrons in undoped semiconductors only. It does not apply to modifications of the crystal.

"I cannot put an apple in a box because there is no box."
"Here I give you a box"
"Now I can put an apple in a box."
 

Similar threads

Undergrad Can Having Electrons in Energy Levels Indicate Ionisation of Atoms?
  • · Replies 2 ·
Replies
2
Views
2K
High School Doping in semicondctors (n type)
  • · Replies 2 ·
Replies
2
Views
3K
Undergrad Donor Impurities and the Forbidden region
  • · Replies 4 ·
Replies
4
Views
2K
Graduate Thermal Properties of the Free Electron Gas: Fermi-Dirac Distribution
  • · Replies 1 ·
Replies
1
Views
4K
Undergrad Hall effect in P-type semiconductors: electron-centric heuristic?
  • · Replies 0 ·
Replies
0
Views
3K
Graduate Band structure after compensation doping
  • · Replies 1 ·
Replies
1
Views
3K
Undergrad Continuous Spectrum and Energy levels of Electrons (Energy Bands)
  • · Replies 7 ·
Replies
7
Views
3K
Undergrad Minority charge carriers - what are these?
  • · Replies 2 ·
Replies
2
Views
3K
Graduate Fraunhofer's multiple slits versus atomic scatteres (diffraction theory)
  • · Replies 6 ·
Replies
6
Views
3K
Undergrad Density of States: 1-Dim Linear Phonons & Electrons Differences
  • · Replies 4 ·
Replies
4
Views
2K