|May3-11, 10:17 PM||#1|
What has bandgap gotta do with binding energy and stability?
Could someone clarify the following statement please?
"ZnO has a bandgap of 3.4 eV at room temperature and a free exciton binding energy of 60meV which is much larger than the room temperature thermal excitation energy (25meV) making them stable at rtp."
Does it mean that at rtp, we will not see spontaneous photoemission?
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|May4-11, 03:39 PM||#2|
Also, one of the objectives from research on ZnO is to make a bound exciton based laser since the BE survives as you said even at RT.
Maybe I didn't understand your question.
|May4-11, 04:45 PM||#3|
However as noted before, spontaneous emission can occur also from ionized carriers. However, as mendes already noted these materials are interesting for applications. Excitons are composite bosons, while unbound ionized carriers are fermions. This means that excitons can in principle undergo bosonic final state stimulation and form a BEC-like state which allows to create spontaneously emitted coherent emission. I think that BEC-like states at room-temperature are interesting goes without saying. So reasonable efforts have been devoted to getting condensates of composite bosons, mostly in terms of polaritons. For ZnO I think the Grundmann group in Leipzig has realized polariton lasing/condensation already.
I suppose this is already more than you asked for. ;)
|bandgap, binding energy, emission, photo, stability|
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