Hi all.
I study the recombination in a direct band-gap semiconductor.
My questioning is that which energy-level the exciting electron settle down when a direct band-gap material exposed by photon (Photoluminescence).
The electrons near the valence band maximum(VBM) jump to the energy states near conduction band minimum(CBM) by the exposure of photon. Then they recombine with the electron-holes in VBM emitting photons. As far as I know, I can understand the excitation and recombination using the concept of the exciton.
By the way, what happens in the case of (electron occupied) impurity level (between band-gap) forming by doping impurity element to the direct band-gap semiconductor?
So, which energy level the electrons in the impurity level jump to? Do they also jump to the energy level near CBM, or the other state of the impurity itself, or the other way of excitation? In my opinion, there would be no corresponding energy state of the impurity level such as the bonding - antibonding state.
In addition, in the condition of the excitation or recombination, should there be spacial overlap between the wavefunctions of the starting and arriving states?
