CrazyEngineers Archive
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@Jeffrey Arulraj • 16 Oct, 2012 • 3 likes

Why is Carbon the first element in the group is not a semi conductor though all the other elements are

@Abhishek Rawal • 16 Oct, 2012 • 1 like C-C bonds forms crystal & electrons are not obtained in crystals as they are tightly bound .Hence it is not used in semiconductor.
@lal • 16 Oct, 2012 • 2 likes Simply saying, there is nothing to carry the current. No free electrons or no holes. Eith valency 4, every electrons in the outermost orbit take part in the bonding.
@Jeffrey Arulraj • 16 Oct, 2012
lal
Simply saying, there is nothing to carry the current. No free electrons or no holes. Eith valency 4, every electrons in the outermost orbit take part in the bonding.
What exactly is the valency of Carbon then
@Abhishek Rawal • 16 Oct, 2012 • 1 like
lal
Simply saying, there is nothing to carry the current. No free electrons or no holes. Eith valency 4, every electrons in the outermost orbit take part in the bonding.
In Si & even in Ge, all e- takes part in formation of covalent bond.
But due to temperature(heat) those bonds are easily broken & e- are produced, resulting in flow of e-.
@Jeffrey Arulraj • 16 Oct, 2012 • 1 like Yeah but can't the same thing be achieved in C it also has only four bonds and so the breaking of bonds can be done right
@Abhishek Rawal • 16 Oct, 2012 • 2 likes Nope as i said C-C covalent bond forms crystal. (eg diamond)
Current in crystal is practically impossible.
Also C6, so electronic configuration is 1s2 2s2 2p2, so more energy is required to remove an e- from the bond.The amount of energy required is not available at room temperature.
So, one of the most essential property of semiconductor is lacking.
@Jeffrey Arulraj • 16 Oct, 2012 So more electrons must be present preferrably the d subshell to tolerate the nuclesr forces and bring down the ionisation potential
@lal • 16 Oct, 2012 • 2 likes Carbon as graphite is but a semiconductor, diamond is not. That means, troll, as u said the crystaline form cant conduct. Right?
@Jeffrey Arulraj • 16 Oct, 2012
lal
Carbon as graphite is but a semiconductor, diamond is not. That means, troll, as u said the crystaline form cant conduct. Right?
But in any cost we use crystalline Silicon but as troll said omit the crystalline carbon for the reason of higher ionisation energy
@Abhishek Rawal • 16 Oct, 2012 Crystalline Carbon cant conduct.
Because C-C are tightly bounded.

But doping can change result (I am not sure though)
SiC is one eg where C is doping element in Si.
@Jeffrey Arulraj • 16 Oct, 2012
Troll_So_Hard
Crystalline Carbon cant conduct.
Because C-C are tightly bounded.

But doping can change result (I am not syre though)
SiC is one eg where C is doping element in Si.
Boss SiC is a compound used as an insulator and not as a semi conductor I am not sure either but Silicon carbide is better known for its high temperature resistance and high insulating properties
@Abhishek Rawal • 16 Oct, 2012 • 2 likes SiC is a semiconductor which is used in high voltage semiconductor electronics.
It is also used in LEDs 'cause it emits "blue" light.
@Jeffrey Arulraj • 16 Oct, 2012 Cool thanks for the info am going to know more of this now 😀
@lal • 17 Oct, 2012 Pretty interesting this is.
@[Prototype] • 17 Oct, 2012 • 2 likes Carbon does exhibits semiconductor property but it will require a lots of energy to work. The more an electron is near to the nucleus, the stronger is the covalent bond. Since carbon has only 2 shells, the valence electrons are pretty tightly bonded, while in case of silicon, its ideal i.e. 3 shells. Germanium is not a preferred semiconductor and is used in very few applications because the valence electrons are so loosely coupled that it starts conduction even at room temperature.

To conclude,

Carbon -> Require lots of energy to work.
Silicon -> Mid range, not to high, not to low.
Germanium -> Very low.

The first and last both are not acceptable. The only reason because Germanium is used as its properties can be controlled, but in case of carbon as TSH mentioned, it just goes to form a crystalline structure.
@Jeffrey Arulraj • 17 Oct, 2012 the Ge threshold also pays a role of it not being popular if my calculations are right the presence of d subshell has brought the break over voltage from over 8 V in C to lesser than 1 V in Si and .3 V in Ge
@sowmiya vd • 17 Oct, 2012 electricity can conduct through carbon but it has no resistance and all electrical energy will be wasted in the form of heat and it forms crystalline structure(diamond).
the latest form of carbon which is known as graphene and it is very superior than other convention semiconductors.
@Jeffrey Arulraj • 17 Oct, 2012 Graphene is more familiar for its Piezo electric nature friend and so this is not a common replacement for Si in the semi conductor region
sowmiya vd
electricity can conduct through carbon but it has no resistance and all electrical energy will be wasted in the form of heat and it forms crystalline structure(diamond).
the latest form of carbon which is known as graphene and it is very superior than other convention semiconductors.
@sowmiya vd • 17 Oct, 2012 • 4 likes graphene conducts electricity 30 times faster than silicon!!but the use of graphene as semiconductor in replacement with silicon is still under research....
link...
https://www.sfgate.com/business/article/Graphene-could-create-faster-semiconductors-2334444.php
@Jeffrey Arulraj • 17 Oct, 2012 • 2 likes
sowmiya vd
graphene conducts electricity 30 times faster than silicon!!but the use of graphene as semiconductor in replacement with silicon is still under research....
link...
https://www.sfgate.com/business/article/Graphene-could-create-faster-semiconductors-2334444.php
Hey friend you are forgetting some thing very important if the conduction is very high then why is it not out in the market now ?

The reason is simple Si and Ge SiC SiAsP all are dependent on the atmospheric temperature only this makes them more predictable in their responses to a great extent the effect of external forces are absent in them

But the Graphene model as far as I know has higher conductivity but poorer stability in real world It is temperature dependent but more dependent on other external forces acting on the crystal due to piezo electric nature.This implies more stability concern extra stabilizers are needed for effective operation
@[Prototype] • 17 Oct, 2012 • 1 like
jeffrey samuel
the Ge threshold also pays a role of it not being popular if my calculations are right the presence of d subshell has brought the break over voltage from over 8 V in C to lesser than 1 V in Si and .3 V in Ge
Totally inter-related with what I said. What is providing voltage? Its giving external energy. What dies temperature do? It gives external energy.
Why Ge starts conduction at room temperature? Evident from neglibile threshold required i.e. 0.3 v.

Thats the reason I have writen energy to genralize it. It could be voltage or temperature.
@Jeffrey Arulraj • 17 Oct, 2012 • 1 like Well true [Prototype] the reason for it having negligible Barrier potential is that that is it no worries though
@ambrish gautam • 14 Apr, 2016 • 1 like Al through carbon belongs to fourth group of periodic table, but properties of carbon are highly unstable, unpredictable . And has a energy band of more than 1.5 ev.
so sometimes carbon is the influence of temperature behave as insulator where as some times carbon works as semiconductor. So that's why we don't consider carbon as semiconductor material.
@Rashmi Gandhi • 31 Jan, 2020

I think that carbon does have some semiconductor properties, but it needs lot of energy to work like one. Carbon has no free electrons available, so it will never conduct electricity. 

For an element like carbon to be considered as a semiconductor it needs to have a certain energy gap. According to theory it needs to be between 0.6 eV to 3.4 eV. 

Since carbon falls in the higher energy gap category (which is 5.5eV), it will not be called a semiconductor. Hope this makes sense. ? 

@Durgesh Srivastava • 31 Jan, 2020

Carbon is a non-metal, and non-metals are poor conductors of electricity because the bond structure is a "close-packed arrangement." Silicon and germanium which are also in Group IVA are semi-conductors and are classified as metalloids. Metalloids show properties of both metals and non-metals. The have low electrical conductivity compared to metals but conduct more than non-metals. This property makes them useful in small scale electronics.

@Kavya Burramolla • 03 Feb, 2020

The basic property of semiconductor is that its conductivity lies between coonductor and insulator. Silicon and Germanium are the two mostly used semiconductor elements. 

Carbon due to its property of not controlling the conductivity not used. Si and Ge acts as the conductors adn insulator dependng up on the voltage levels supplied. There is a term called cut off voltage in the semiconductors which when crossed by the supplied input voltage the semiconductor acts as the Conductor and below the cut off voltage it acts as Insulator. The cut off voltage for Ge and Si are  0.3 and 0.7 respectively. Once the device is operated above these voltages it works as conductor and less than that acts as insulator. Carbon will not have this property to control the conductivity. A pure carbon can never be used as an insulator, hence cannot be used as a semiconductor.

@Venkat Sai Nakkina • 03 Feb, 2020

Nope as i said C-C covalent bond forms crystal. (eg diamond)
Current in crystal is practically impossible.
Also C6, so electronic configuration is 1s2 2s2 2p2, so more energy is required to remove an e- from the bond.The amount of energy required is not available at room temperature.
So, one of the most essential property of semiconductor is lacking.

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