Hey, I have few doubts in Solid state physics specially related to Image charge & Brillouion zone. I read several books regarding this matter but still my concept is unclear. Can you kindly answer my following questions:- 1) What is meant by Image charge? When it´s formed? What is its significance? In the case of Schottky contact between metal & Semiconductor interface, how does it cause lowering of the barrier? 2) What is Brillouin zone? What is its physical significance? When one is supposed to take the Brillouin zone picture into account? Thanking you for your time.