As thermal fluctuations cause the dopant-associated majority charge carriers to diffuse across a p-n junction, one side (the p-type side) becomes electrically negative and the other side (the n-type side) becomes electrically positive: two sheets of opposite charge create an electric field. Associated with an electric field is a voltage drop, where the higher potential is on the positive charge side (which is the n-type side into which positive holes from the p-type side have burrowed). The electron energy is higher on the p-type side.