Semiconductor Physics: Band Formation and Experiments

This lecture focuses on the formation of bands in semiconductors and presents three significant experiments related to this topic. The instructor begins by discussing the behavior of charge carriers in conductive plates, illustrating how applying a magnetic field can reveal the sign of the carriers. The first experiment demonstrates how replacing atoms in silica with dopants like boron or phosphorus can alter the charge carrier type. The second experiment involves cyclotron resonance, which helps determine the effective mass of charge carriers by observing their behavior in a magnetic field and under microwave radiation. The instructor explains how the mass of electrons varies with the orientation of the magnetic field, introducing the concept of effective mass as a tensor. The final experiment showcases the wave-particle duality of electrons through a double-slit experiment, where individual electrons create interference patterns over time, highlighting the complex nature of electrons in quantum mechanics. This comprehensive overview emphasizes the intricate relationship between structure, charge carriers, and their behavior in semiconductor materials.