How Is the Energy of the Conduction Band Determined in N-Doped Germanium?

[abdo799]

I am studying introduction to solid state physics and it's stated that when germanium is n doped energy states with energy -0.1 ev are introduced, then it's stated that this means that the donor level is 0.1 ev below the Conduction level
Does that mean that the Ec is considered 0??

 

[Simon Bridge]

the donor level is 0.1 ev below the Conduction level ...

...means that whatever E_c is, the donor level is E_c-0.1eV.

 

[abdo799]

...means that whatever E_c is, the donor level is E_c-0.1eV.

i thought so in the first, but when i revised his calculation ( and checked another text) this energy is not a difference, when he was trying to calculate an approximate he used the bohr model. FIRST he said it was -0.1ev then he said thus it's -0.1 ev below it.
i can screenshot it for you if you would understand more if u saw the text.

 

[nasu]

He calculates how much energy (minimum value) is needed to free the electron from its atom. This means to "move" it into the conduction band. If you need 0.1 eV to promote it into the conduction band, where would you locate the initial state?