(a) Design a N-type semiconductor (Phosphorus) based on Si that allows a constant conductivity of 50 (12.m) at room temperature. The mobility of the carriers is 0.135 m/ Vs. [6 marks] [CO2, PO3, C3] (b) At temperature near room temperature (298 K), the temperature dependence of the conductivity for intrinsic germanium is found to equal with this equation below Eg o = CT-3/2exp(- 2KT where C is the temperature-independent constant and T is in Kelvin. Using the given equation, calculate the intrinsic electrical conductivity of germanium at 200 C. (Eg value is 0.67 eV, and at room temperature the conductivity is 2.2 (12.m)')