Doped semiconductors guiferra - Sat, 06/18/2016 - 03:55 Excellent, understandable and efficient explanations, my compliments. However, something it is not completely clear with the explanation of number of carriers available for conduction in N-type semiconductors. In fact, if it is true that the fifth electron of dopant phosphorous has no silicon atom with an available covalence bound in its surroundings to be bound with, it is still true that that electron should still be bounded to the phosphorous atom. So why it is available for conduction, is the bound to its atom so weak when it does not take part of a covalent bound? Which energy is necessary to take it out from its atom compared with the energy necessary to break a covalence bound? I will appreciate any comment to this.