Question

In a uniformly doped BJT, assume that $N_E,N_B$ and$N_C$ are the emitter, base and collector dopings in $atoms/c{m}^3$, respectively. If the emitter injection efficiency of the BJT is close to unity, which one of the following is TRUE?

• A. $N_E=N_B$ and $N_B$
• B. $N_E>>N_B$ and $N_B>N_C$
• C. $N_E<N_B<N_C$
• D. $N_E=N_B=N_C$

Answer 1

The correct option is B $N_E>>N_B$ and $N_B>N_C$

Ans : (b)

$\gamma =\frac{1}{1+\frac{N_B}{N_E}}$
To achieve $\gamma =1$
$N_E>>N_B$