Question

If $N^A$ is number density of acceptor atoms added and $N^D$ is number density of donor atoms added to a semiconductor, $n^e$ and $n^n$ are the number density of electrons and holes in it,then

• A. $n^e=N^D,n^n=N^A$
• B. $n^e=N^A,n^h=N^D$
• C. $N^A+n^n=N^D+n^e$
• D. $n^e+N^A=n^n+N^D$

Answer 1

The correct option is C $N^A+n^n=N^D+n^e$

Number of electrone = $n^e$

Number of holes=$n^n$

Number of additional electrons=number of donor atoms added=$N^D$

Number of additional holes=number of acceptor atoms added=$N^A$

Since the lattice as a hole is neutral,

=> $N^A+n^n=N^D+n^e$