Can electron stay between donor energy level and valence band?

In summary, the conversation discusses the concept of donor energy level and its relation to the Fermi level in an n-type semiconductor. The donor energy level is fixed and located below the conduction band, while the Fermi level varies and acts as a reference line for electron occupancy. It is clarified that the Fermi level is not an actual energy level and electrons of an intrinsic semiconductor cannot reside in the energy gap. The conversation also confirms that the conduction and valence band are the energy levels present in an intrinsic semiconductor.
  • #1
Outrageous
374
0
In n-type semiconductor, Can electron stay between donor energy level and valence band?
Can I say that the donor energy level here refer to the Fermi level?

Thank you
 
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  • #2
No, donor energy level is different than fermi level. Donor energy level is fixed w.r.t other energy levels (like 0.01 eV below conduction band). But fermi level varies after equilibrium is reached (like after dopant insertion and equilibrium fermi level will rise up).

Everything b/w conduction and valence band is forbidden except donor and acceptor levels. So, electrons can only stay in donor or acceptor levels if b/w conduction and valence bands. (if defect/surface/recombination states are ignored)
 
  • #3
Thank you
Then in n-type semiconductor , there will be conductn band ,valence band , donor energy level and Fermi level at the same time?
 
  • #4
Yeah, four of them will be there. But, remember the fermi level, itself, does not designate any energy level(slot) where electrons can reside. Its just a reference line which determines how electrons will be populated.
 
  • #5
Kholdstare said:
Its just a reference line which determines how electrons will be populated.

You make this statement because Fermi level is a level that has a probability of 50% to be occupied by electrons at any given temperature?

And one more: electrons of intrinsic semiconductor can't stay at energy gap except Fermi level ?
 
  • #6
Outrageous said:
You make this statement because Fermi level is a level that has a probability of 50% to be occupied by electrons at any given temperature?

And one more: electrons of intrinsic semiconductor can't stay at energy gap except Fermi level ?

You're confusing fermi level with energy level. Fermi level is not an energy level as it cannot hold any electron. Its a reference line which determines electron occupancy. Occupancy means probability of presence of electron IF there is an energy level ALREADY present. So even if fermi level is lying inside forbidden energy gap, no electron will be present in it.

electrons of intrinsic semiconductor can't stay anywhere inside the energy gap.
 
  • #7
Kholdstare said:
Its a reference line which determines electron occupancy. Occupancy means probability of presence of electron IF there is an energy level ALREADY present. So even if fermi level is lying inside forbidden energy gap, no electron will be present in it..

In intrinsic semiconductor, the energy level ALREADY present refers to the conduction and valence band ,right?
 
  • #8
Outrageous said:
In intrinsic semiconductor, the energy level ALREADY present refers to the conduction and valence band ,right?

Yeah. That's right.
 
  • #9
Thanks a lot.
 

1. What is the donor energy level and valence band?

The donor energy level is a specific energy level within a material's atomic structure that is associated with the presence of a donor impurity. The valence band, on the other hand, is the highest energy band of electrons in a material that are involved in bonding with other atoms.

2. Can an electron stay between the donor energy level and valence band?

Yes, an electron can stay between the donor energy level and valence band as long as it has enough energy to occupy that space. However, this is typically a short-lived state as the electron will eventually either drop down to a lower energy level or move up to a higher energy level.

3. What is the significance of an electron staying between the donor energy level and valence band?

The presence of an electron between the donor energy level and valence band can have important implications for the material's electronic properties. This can affect its conductivity, optical properties, and even its ability to act as a semiconductor.

4. How can an electron stay between the donor energy level and valence band?

An electron can stay between the donor energy level and valence band through various mechanisms such as absorption of light, thermal excitation, or through the presence of electric or magnetic fields. Additionally, the material's composition and structure can also play a role in determining the likelihood of an electron occupying this space.

5. What are some potential applications of electrons staying between the donor energy level and valence band?

The ability to control and manipulate the location of electrons between the donor energy level and valence band has promising applications in various fields such as optoelectronics, quantum computing, and energy storage. For example, this phenomenon can be utilized in designing more efficient solar cells or creating faster and more powerful electronic devices.

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