ANSWER: Electron Mobility, Electron Mass

Naveen
mobility!!!

it might seem confusing to claim electronmobility is greater than hole mobility. infact it is true as for a a undoped semiconductor e mobility is twice hole's... HOW

its just the way we define holes and electrons
hole is a vacancy of electron...

but the electrons which generate holes and what we call hole current are different from the electrons that constitute wha we call electron current...

hole current is hue to electron vacancies in valance band...

electron current is due to flow of electrons in conduction band...

so the mobility issue is therefore obvious... hope thats clear...

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ASH007
@ Gourab

Thanx to RP for posting this nice forum.
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abt Mobility.........
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It seems that ur confused about mobility between electron and holes, or positive charge and negative charge. It is well known that negative charge i.e. electron is highly mobile than positive charge i.e. ion because of its mass. Here positive ion is the molecule that lost one of its electron and got +ve polarity. Due to its bulky structure and mass 1800 times greater than electron become less mobile.
Whereas Hole mobility is virtual moment its is actually movement of electron leaving behind its vacancy.


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Its Gourab
@ ASH 007 about Mobility

ASH 007 u write that ----------->

"electron is highly mobile than positive charge i.e. ion because of its mass. Here positive ion is the molecule that lost one of its electron and got +ve polarity. Due to its bulky structure and mass 1800 times greater than electron become less mobile."

U are making some confusion between +ve Ion & Hole . Holes r the absense of electron from a bond not the positve ion . Ok .

I have no confusion about electrons higher mobility ............ I am asking the reson behind that.


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Its Gourab
Mobility !!! @ Naveen

Thnx 4 ur reply.

But !!!!!!! I am asking about the Reason of high mobility of electron than the holes, which is not clear frm ur post.


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RP
Mobility

When we are talking about hole mobility we are not taking about positive ion mobility. So mass goes out of the window. Yes, the energy required to move a hole is much more than the electron, and that as has been vaguely pointed out in mails earlier is the leading cause of slow hole mobility, but physically, electron moves as a body, and hole moves as an empty space through the atomic structre with a pull against the move from all the atoms surrounding it.

Thats my thinking, that hole gets electric field exerted resistance from pull all around.


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Its Gourab
But.......... RP

Hi Rp , u told that "hole moves as an empty space through the atomic structre with a pull against the move from all the atoms surrounding it. "

Hole is a empty space is right. But holes faces a pull to move ? Why ????????


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RP
@mobility

posted question outside forum for better visibility - I think you need quantitative analysis Gaurab. I am sure there is a lot of stuff on this one, but I am rusty. Dont remember right now correctly, and cannot also see any links explaining this mathematically quickly.

Lets see if anyone here in Forum or outside can reply!!!


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Naveen
Hi Gaurab...

Its obvious that electron in conduction band is more mobile than that in Valence band.... What more to explain on that.... Valence band is tied to atom...