(a) for three p-n junction diode samples a, b, and c, acceptor and donor carrier concentrations are the same 1015/cm3 and 1018 /cm3, respectively. band gaps for the three samples a, b, and c are 0.6 ev, 1.4 ev, and 1.9 ev, while the electron and hole effective masses of density of states are the same in all the three materials, me = 0.05m0 and mh = 0.2m0, where is the electron mass in free space. find the built-in potentials for these three devices at t = 300 k. comment on the comparison of estimated built-in potentials.