Understanding Fermi Level in Silicon: Valence and Conduction Bands Explained

[tot]

what I've been told there is two groups of energy levels called the valence and the conduction band.

what is the fermi level for silicon?
how wide is the band gap for silicon?

 

[Bashkir]

Well, if we are talking about intrinsic silicon (undoped silicon) then the fermi energy is directly in the center of the band gap. This means that the concentration of holes and electrons is equal. Doping the silicon will move the fermi energy towards the valence band or the conduction band depending on the doping.

The band gap for silicon is 1.12eV

E_f - E_i = kT ln\frac{n}{n_i}

 

[tot]

is 1.12eV the width of the band gap or the fermi level?
what is the fermi level for undoped silicon?

 

[Bashkir]

That is the width of the band gap as I stated in the last post. The fermi level for undoped silicon lies directly inbetween the conduction band and the valence band. I have also provided you with the equation that you need to find the fermi level.

 

[tot]

i don't understand the equation. please explain how you find the fermi level

 

[Sunfire]

The band gap of Si is seen in this image
http://upload.wikimedia.org/wikipedia/commons/0/04/Band_structure_Si_schematic.svg

band gap = Ec-Ev = 1.1 eV, as shown in the image