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PN Junction Information3 and 5 March 2014

Charge distribution in the depletion region Electric potential in the

depletion region

E-field in the depletion region

In the p-region

),( nx

d xxeN

E

In the n-region

)( px

a xxeN

E

ndpa xNxN

(due to charge neutrality or E-field continuity)

x

pa

x

ndxeNxeN

E

max

In the p-region

2)(2

1p

x

a xxeN

In the n-region

2

2

1)2(

2

1p

x

dn

x

d xeN

xxxeN

22

2

1pand

xbi xNxN

eV

2

Summary of PN Junction under Equilibrium Condition

22

2

1pand

x

bi xNxNe

V

2ln

i

dabi n

NNkTeV

ndpa xNxN

dad

abisn NNN

N

e

Vx

12

daa

dbisp NNN

N

e

Vx

12

da

dabispn NN

NN

e

VxxW

2

xp xnW

33

The PN Junction and Band Diagram

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