A silicon sample has a length of 1micro meter. The N-type doping concentration varies linearly from Nd(x=0) = 10^16 cm-3 to Nd(x=1 micro meter) = 10^17 cm-3. The electron mobility is 1000 cm^2/V.s Problem Figure (a) Assume that no external bias is applied to the sample. Calculate analytically the internal electric field, €o(x) (unit: V/cm) and calculate the numerical value of the electric field at x=0.5 micro meter. (b) Assume that an external bias is applied in order to cancel out the electric field at x = 0.5micro meter .What is the current density in the sample?