Bonds in Semiconductor crystals

In summary, the conversation discusses the confusion surrounding the representation of covalent bonds in semiconductor crystals, specifically in Si and Ge. While these bonds are typically shown in 2D structures, it is known that there are only 4 electrons available for bonding in the upper shell. It is then questioned how this can accurately represent the third dimension in a 3D crystal. It is later clarified that the 2D structures are oversimplifications and that the actual structures are diamond-like with consideration for orbital hybridization.
  • #1
19Stan
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0
Hi!
I study semiconductors and I am confused with the bonding picture for semiconductor crystals. For example, it is said that in Si crystal one can find covalent bonds. In the most books this bonds are shown like that: 2D crystal structure where lines between atoms are a covalent bonds, each line stands for one electron (like here http://www.aplusphysics.com/courses/honors/microe/silicon.html). At the same time it is well known that in Si or in Ge there are only 4 electrons on the upper shell: two s electrons and two p electrons, only these ones can form bonds. Therefore it follows that for such 2D pictures of Si or Ge crystals we are just running out of electrons to make covalent bonds for the third dimension (usual crystal has 3D)!
Can you please explain what's going on with the third dimension. If such representations which i mentioned above is not true (or partially true), then what is complete 3Dimentional picture for bonding in semiconductors should look like?
 
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  • #2
It seems i found the answer: those 2D pictures are huge simplifications. in reality Si and Ge have diamond structures. Plus you have to keep in mind orbital hybridization. Here is the best description of semiconductor structures and bonding:
 
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FAQ: Bonds in Semiconductor crystals

1. What are the types of bonds present in semiconductor crystals?

Semiconductor crystals typically have covalent, ionic, and metallic bonds present. Covalent bonds involve the sharing of electrons between atoms, ionic bonds involve the transfer of electrons between atoms, and metallic bonds involve a sea of delocalized electrons binding the atoms together.

2. How do the bonds in semiconductor crystals affect their properties?

The type and strength of bonds present in a semiconductor crystal can greatly influence its properties. For example, covalent bonds result in a strong and rigid structure, while metallic bonds allow for high electrical and thermal conductivity.

3. How do impurities affect the bonds in semiconductor crystals?

Impurities, or dopants, can introduce new energy levels within the band structure of a semiconductor crystal. This can affect the distribution of electrons and holes, and ultimately impact the conductivity and other properties of the crystal.

4. How are bonds broken and formed in semiconductor crystals?

Bonds in semiconductor crystals can be broken and formed through various processes, such as thermal energy, light, or electrical current. For example, in a p-n junction, bonds can be broken and formed to create a depletion region, allowing for the flow of current.

5. Can the bonds in semiconductor crystals be manipulated?

Yes, the bonds in semiconductor crystals can be manipulated through processes such as doping, alloying, or strain engineering. These methods can alter the properties of the crystal, making it more suitable for specific applications.

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