1. Calculate the built-in potential barrier, $V_{bi}$, for Si, Ge, and GaAs pn junctions if they each have
the following dopant concentrations at T = 300 K:
(i) For Si, acceptor concentration, $N_a = 10^{14} cm^{-3}$ and donor concentration, $N_d =$
$10^{17} cm^{-3}$
(ii) For Ge, acceptor concentration, $N_a = 5 \times 10^{16} cm^{-3}$ and donor concentration, $N_d =$
$5 \times 10^{16} cm^{-3}$
(iii) For GaAs, acceptor concentration, $N_a = 10^{17} cm^{-3}$ and donor concentration, $N_d =$
$10^{17} cm^{-3}$