At an equilibrium temperature of 50\deg C, the contact
potential of a pn junction is 0.6 V . The intrinsic carrier
concentration is n_(i)=1.5\times 10^(10)(1)/(c)m^(3), and the donor con-
centration in the n-type material is 7.0\times 10^(17)(1)/(c)m^(3).
The acceptor concentration is most nearly