What is depletion accumulation inversion in terms of bands?

[Bert F]

accumulation depletion inversion

I try to understand depletion inversion and accumulation in terms of band bending however I have found an example where the say that the bands are in depletion and inversion:

Who can I deduced what the band will do in inversion or in the depletion?
When will the band bend toward or upward? In what type of configuration? Inversion or depletion?

Thanks.

 

[subharpe]

what is depletion

In a band when fermi level crosses the intrinsic level due to application of voltage (bending) inversion takes place.

A p type channel device has the fermi level below the intrinsic level. Due to application of gate voltage the band bends upward and eventually crosses the intrinsic level. In that condition it has a fermi level above intrinsic level and hence it transforms to a n channel and therefore starts conducting.

 

[Bert F]

depletion accumulation

Thanks for replying.