1. The problem statement, all variables and given/known data Can anyone explained to me the factor of 2 in the equation for the intrinsic carrier concentration? 2. Relevant equations ni is proportional to exp(-Eg/2kT) where ni is the intrinsic carrier concentration, Eg is the band gap energy, k is Boltzmann's constant, and T is temperature in Kelvins. 3. The attempt at a solution I understand that there are two charge carriers (a hole in the valence band and a free electron in the conduction band), but I don't understand why it is Eg/2 and not 2Eg.