0
\$\begingroup\$

I could find references for describing the depletion layer in a power diode under reverse bias and the consequent classification of Non-punch through and Punch-through diodes.
But I couldn't find a satisfactory explanation of how the depletion layer looks like under no bias. How far does the depletion layer extend into the n- layer? My guess is that the depletion layer width is small in the heavily dopes p+ region and large in the lightly doped n- region (but less width than in reverse bias condition).

\$\endgroup\$
0
\$\begingroup\$

It is impossible to answer your question without knowing the (relative) doping levels and the width of the N region.

Usually in power diodes the n region is lightly doped and also wide to increase the reverse breakdown voltage.

At zero bias the charges in the N and P depletion regions are be the same. So if the P+ region has 2x the doping level of the N region, the P+ depletion region will be 1/2 as wide as the N depletion region.

If the N region is wide enough to contain the complete depletion region (it does not reach the N+ part) then the relative sizes of the depletion regions will match the relative doping levels.

If the N region is not wide enough to contain the complete depletion region so part of it is inside N+ region then things get more complex.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.