In a semiconductor p-n diode, the doping concentrations on p-side and n-side are 1015 atoms/cm3 and 1018 atoms/cm3, respectively. Which one of the following statements is true ?
- Widths of depletion region on either side of the interface are equal
- The depletion region width is more on p-side compared to that in n-side
- The depletion region width is more on n-side compared to that in p-side
- No depletion region forms because of unequal doping concentrations on p and n-sides
Answer
(2) The depletion region width is more on p-side compared to that in n-side
Solution
Overall charge neutrality of the depletion region: NAxp=NDxn
xpxn= NDNA= 10181015=103
the depletion region spreads much more into the lightly doped p-side.
A depletion region always forms at a p-n junction, whatever the doping (4) is wrong.
The depletion region width is more on p-side.
Answer: (2)