An  -n Silicon device is fabricated with uniform and non-degenerate donor doping concentrations of N_D1=1×10¹⁸ cm^-3 and N_D2= 1×10¹⁵ cm^-3 corresponding to the n⁺ and n regions respectively. At the operational temperature T, assume complete impurity ionization, kT/q = 25 mV, and intrinsic carrier concentration to be n_i= 1×10¹⁰ cm^-3. What is the magnitude of the built-in potential of this device?