513.001 Molecular and Solid State Physics

pn junction

A silicon pn junction is doped with 10¹⁷ cm^-3 donors on the n-side and 10¹⁷ cm^-3 acceptors on the p-side.

(a) Calculate the chemical potentials on the two sides at 300 K. Set the zero of energy to be at the top of the valence band.

(b) Calculate the built in voltage for this diode. If you did not find the chemical potentials in part (a), use μ_n = 1 eV and μ_p = 0.1 eV.

(c) Draw the electric field as a function of position indicating the direction the field is pointing.

For silicon: E_g = 1.12 eV, N_c = 2.78×10²⁵ m^-3 and N_v = 9.84×10²⁴ m^-3.