In metal, fermi energy is the highest energy states that electron occupied at T=0. And so, fermi energy of a particular metal is an intrinsic value, and won't be changed. Then for a semiconductor, What is fermi energy, is there any concrete interpretation as of metal? Why is it just in the middle of energy of VB and CB? Besides adding impurities, would the fermi energy of a SC changed according to, say, temperature? Thank you for your kindly reply!!