Low-field and high-field transport, introduction to diffusion

[@mytreyak]

10:28 if someone is wondering about the equation 1/(total_mobility) = 1/(mobility_phonons) + 1/(mobility_ionization) -- [0] , consider the collisions per second in each category.. collisions_per_second_phonons = (charge/effective_mass)*(1/mobility_phonons) --[1] collisions_per_second_ionization = (charge/effective_mass)*(1/mobility_ionization) --[2] total_collisions_per_second = (charge/effective_mass)*(1/mobility_total) --[3] total_collisions_per_second = collisions_per_second_phonons + collisions_per_second_ionization --[4] [1] through [4] will lead to [0] Of course if your math is fresh, then all this is not required, its the probability of any of the two independent events (collisions due to phonons or collisions due to ions) occurring

[@Neeraj-is1jt]

At 10:23 how can he say mobility due to phonon and mobility due to impurity atoms, shouldn't the mobility is due to charge carriers like electrons or holes?

[@pvaishnavi8615]

Mobility is caused due to scattering and scattering is because of impurity and phonons

[@Neeraj-is1jt]

@@pvaishnavi8615 ok thanx for the contribution

[@louerleseigneur4532]

Awesome Thank you very much sir

[@alanjoy7915]

Nice lecture

[@NidBM]

Trueeee

[@tarutewari]

sir the lectures are commendable but if you could just name them it would of great help thanku

[@freeandreliablejeeprep820]

thank you v and krishna

[@madagalarajasekhsar3739]

excellent .

[@freeandreliablejeeprep820]

thank you sir

[@ahmedatifabrar7698]

At 34:05, it's diffusion current density, not diffusion current.

[@andydufresne436]

@16:00 flux = nv_d. Isn't flux a kind of total, at the moment.. a quantity which increase with area considered. E.flux is total field lines in an area or a plane, at the moment.. ( E.field is force per charge at the moment ). n (unit = cm-3) , v (unit = cm.s-1) . So here, flux is something per area per second , which doesn't increase with the area considered.. Can anyone explain, how it is flux in this equation??

[@madagalarajasekhsar3739]

why half of the electrons only move from either sides

[@KaviPriyan-qt6vc]

same doubt

[@vikramaditya4959]

@@KaviPriyan-qt6vc when there is no field applied then due to thermal energy probabilistically half move left and another half move right as the motion is random

[@madagalarajasekhsar3739]

sir how high doping results in lesser mobility

[@gautamjha829]

yes,you can relate when concentration increases Speed decreases .

[@hari4160]

High doping will result in more number of impurity ions which causes more scattering which results more collisions ,less distance Hence mobility decreases as tow decreases

[@Neeraj-is1jt]

At 3:40 how mobility is different for different material , as it depends only on effective mass of electron?

[@BPHVAIBHAVSHARMA]

Because effective mass also depends upon the potential it is going through and hence material.

[@080vyas9]

sir at @27.28 how can u say that exactly half goes right and half goes left as the concentration is more on the left side

[@animeshgautam6197]

since its a random motion therefore its probability will be 0.5

[@Neeraj-is1jt]

At 10:23 how can he say mobility due to phonon and mobility due to impurity atoms, shouldn't the mobility is due to charge carriers like electrons or holes?

[@andydufresne436]

μₚₕₒₙₒₙ : Mobility of carriers (electrons or holes) due to the effect of _phonons_. μᵢ.ᵢₘₚ : Mobility of carriers due to the effect of _Ionised_ _impurities_. - each define the mobility due to the respective condition. _Mu_(total) gives the *actual mobility*.

[@baluanyam8751]

00:26

[@sanjusingha1714]

Note 11:55 21:35

[@MrVishalbharti]

Dear sir, there is an error at 31:48 time. The value of delta x should be 2l not single l. Please check it.

[@utkarshpandey6508]

No, my friend. It will be l. Take the points on curve at height nL and nR. They are l distance apart.

[@madagalarajasekhsar3739]

@@utkarshpandey6508 how it is l bro

[@utkarshpandey6508]

@@madagalarajasekhsar3739 delta x = (x not + l/2) - (x not - l/2) = l/2 + l/2 = l