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Basic queries of semiconductor devices

by shaikss
Tags: basic, devices, queries, semiconductor
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Nov23-11, 05:10 AM
P: 33
I have few queries regarding the below Qs.

1. How does the fermi level vary with distance under both equilibrium and non-equilibrium conditions? Is it constant or varying under equilibrium and non-equilibrium conditions?
My query>> Fermi level vary with temp. But I am not getting how to analyse how fermi level changes w.r.t distance.
2. what happens to fermi energy level when temp is increased in n-type semiconductors?
My explanation>> When temp is increased, donor electrons move from valence band to conduction band and so is the fermi level. At the same time, when the increase is temp is very high, there is a point where the affect of doping is neglible when compared to affect of increase in temp. So, the fermi level moves more deeper into the forbidden energy and so fermi level approches mid level of the energy gap and becomes intrinsic. Is this correct? Or had i missing something in my analysis?
3. When donor impurity concentration is increased, what happens to fermi level position?
My explanation>> Fermi level varies with doping concentration. fermi level moves towards the conduction band edge in case of N-type semiconductor and towards Valence band in case of P-type SC. Am I wrong at any point?
4. As the temperature is increased from 0 K, what happens tothe mobility of a moderately doped semiconductor?
My explanation>> Mobility increases to certain level afterwards it starts decreasing.

Please let me know whether my analysis is correct and correct me if I am wrong at any point.
Do tell me how fermi level vary with temperature.

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