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Douasing
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Why is black phosphorus a semiconductor with a direct bandgap?
The problem is mentioned by the two following references:
"The three bonds take up all three valence electrons of phosphorus,so, unlike graphene, monolayer black phosphorus is a semiconductor with a predicted direct bandgap of 2 eV at the G point of the first Brillouin zone."
(see http://www.nature.com/nnano/journal/v9/n5/full/nnano.2014.35.html)
"Unlike carbon, phosphorus has only three valance electrons which leads to BP being semiconducting since each atom is bonded to three neighboring atoms."
(see http://scitation.aip.org/content/aip/journal/apl/104/10/10.1063/1.4868132)
In order to check the point,I input the keyword "valence" in wiki:
http://en.wikipedia.org/wiki/Valence_(chemistry)
I found that typical valencies are three and five for phosphorus,but only four for carbon.I somehow doubt the explanation in the references and some meticulous and clear details shoud be supplied.
The problem is mentioned by the two following references:
"The three bonds take up all three valence electrons of phosphorus,so, unlike graphene, monolayer black phosphorus is a semiconductor with a predicted direct bandgap of 2 eV at the G point of the first Brillouin zone."
(see http://www.nature.com/nnano/journal/v9/n5/full/nnano.2014.35.html)
"Unlike carbon, phosphorus has only three valance electrons which leads to BP being semiconducting since each atom is bonded to three neighboring atoms."
(see http://scitation.aip.org/content/aip/journal/apl/104/10/10.1063/1.4868132)
In order to check the point,I input the keyword "valence" in wiki:
http://en.wikipedia.org/wiki/Valence_(chemistry)
I found that typical valencies are three and five for phosphorus,but only four for carbon.I somehow doubt the explanation in the references and some meticulous and clear details shoud be supplied.
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