Surface Properties: Understanding Semiconductors and Nanomaterials

This lecture focuses on the properties of surfaces and interfaces in semiconductors and nanomaterials. It begins with a discussion on the differences between bulk and surface materials, emphasizing the significance of unsaturated bonds at surfaces. The instructor explains how surface energy varies with different crystal planes and how this affects atomic arrangements. The concept of surface reconstruction is introduced, illustrating how atoms adjust their positions to minimize energy. The lecture also covers the impact of external conditions on surface states and the behavior of semiconductors, including phenomena like band bending and charge accumulation. The instructor highlights the importance of surface passivation in nanostructures, particularly in quantum dots, to enhance optical properties. The session concludes with a discussion on the implications of surface states in metal-semiconductor contacts, including the formation of Schottky barriers and Ohmic contacts. Overall, the lecture provides a comprehensive overview of how surface characteristics influence the functionality of semiconductor materials.