Understanding Semiconductor Behavior: Charge and Conductivity

This lecture discusses the behavior of semiconductors, focusing on the energy levels and charge distributions within N-P-N structures. The instructor begins by analyzing the energy levels in a semiconductor structure, noting the positions of the Fermi energy relative to the conduction and valence bands. The discussion includes the effects of charge curvature and electric fields, highlighting how these factors influence the overall conductivity. The instructor explains the relationship between temperature and carrier concentration, detailing how intrinsic and extrinsic regions behave differently as temperature changes. The lecture also covers the concept of conductivity as a tensor relating current density to electric field, emphasizing the role of mobility and temperature dependence. The final part of the lecture examines the interface between metals and semiconductors, illustrating how energy levels align and the resulting charge distributions. The instructor concludes with a detailed analysis of the electric field behavior in these structures, providing insights into the practical implications for semiconductor devices.