Lecture
This lecture discusses the concept of effective masses in semiconductor physics, focusing on the formation of energy bands and their implications for materials like silicon and gallium arsenide. The instructor explains the differences between metals, semiconductors, and insulators, highlighting the role of band gaps and effective mass in determining electrical properties. The lecture covers the dispersion relations and the effective mass approximation, detailing how these concepts relate to the behavior of charge carriers in semiconductors. The discussion includes examples of effective masses for various materials and their significance in device applications. Additionally, the instructor addresses the anisotropy of effective masses and its consequences for piezoresistive effects in silicon. The lecture concludes with practical applications and measurements related to band gaps and absorption coefficients, providing a comprehensive overview of the topic.