BJT punchthrough effect.

[ljy4468]

punchthrough bjt

Hi
I've a question about punchthrough of BJT.

When CB depletion region extends further as Vcb increases,
CB depletion region will meet EB depletion region, eventually.
Then, Ic increases increases.

I understand above fact with energy band digram model.

But, I cannot understand another way.
That is..

npn of punchthrough seems to be -(depletion region)-.
Then how current goes through depletion region??
By E-field??

 

[Abhishekabs]

I can Suggest two books which can clear your doubts
1) Solid state physics by B.G Streetman
2) Physics of Semiconductor devices by S.M.Sze

 

[ravi_free]

i have same doubt, anyone can give short description on this ?
how current goes through depletion region in punch-through??