Why is black phosphorus semiconductor with direct bandgap?

In summary, black phosphorus is a semiconductor with a direct bandgap due to its three valence electrons bonding with neighboring atoms. This is in contrast to carbon, which has four valence electrons and is not a semiconductor. Further information can be found by researching the valence of phosphorus and carbon.
  • #1
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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.
 
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  • #2
p has a full s orbital and 3 additional electrons in the remaining three p orbitals. Hence these three orbitals can form 3 covalent bonds with neighbouring atoms. There are also 3 anti-bonding orbitals at higher energy. The bonding orbitals will form a full valence band and the anti-bonding orbitals an empty conduction band.
 

Related to Why is black phosphorus semiconductor with direct bandgap?

1. Why is black phosphorus a semiconductor?

Black phosphorus is a semiconductor because it has a unique electronic structure that allows it to act as an insulator at low temperatures and a conductor at high temperatures.

2. What is the direct bandgap in black phosphorus?

The direct bandgap in black phosphorus refers to the energy difference between the highest occupied energy level (valence band) and the lowest unoccupied energy level (conduction band) being at the same point in momentum space. This allows for efficient electron transitions and makes black phosphorus a more efficient semiconductor compared to other materials with an indirect bandgap.

3. How does the bandgap affect the electrical properties of black phosphorus?

The direct bandgap in black phosphorus allows for efficient electron transitions, making it a more efficient semiconductor. This means that it can easily switch between being a conductor and an insulator, making it useful for electronic devices.

4. Why is black phosphorus considered a promising material for future electronics?

Black phosphorus is considered a promising material for future electronics because of its unique electronic structure and direct bandgap. This makes it more efficient and versatile than other semiconductors, allowing for faster and more energy-efficient devices.

5. How is the direct bandgap in black phosphorus different from other semiconductors?

The direct bandgap in black phosphorus is different from other semiconductors because it allows for more efficient electron transitions, making it a more efficient semiconductor. Other materials may have an indirect bandgap, which means the highest occupied energy level and lowest unoccupied energy level are at different points in momentum space, making electron transitions less efficient.

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