1 / 9

INTRODUCTION TO QUANTUM THEORY OF SOLIDS

INTRODUCTION TO QUANTUM THEORY OF SOLIDS. By Sushama Baag. CHAPTER OBJECTIVE. LECTURE-1. This chapter provides the basic concepts and terminology for understanding semiconductors. Importance is given to the concepts of energy band ,

noah
Download Presentation

INTRODUCTION TO QUANTUM THEORY OF SOLIDS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. INTRODUCTION TO QUANTUM THEORY OF SOLIDS By Sushama Baag

  2. CHAPTER OBJECTIVE LECTURE-1 • This chapter provides the basic concepts and terminology for understanding • semiconductors. • Importance is given to the concepts of energy band , • 2 kinds of electrical charge carriers called electrons and holes • and how the carrier can be controlled with addition of dopants. • Another important fact is the Fermi distribution function and • concept of Fermi level. • The electron and hole concentration are closely linked to Fermi level. • Mastery of the terms , concepts and models presented here will prepare • you for understanding not only the many semiconductor devices that • are in existence today but also many more that will be invented in the future.

  3. Before the “How” , Ask Yourself “Why” • Before we dive in, we’ll take a moment to explain exactly why we’re so interested in, and dependent on semiconductors in the first place. • Semiconductors are so important to our electronic devices simply b’coz their properties can be easily and substantially manipiulated.

  4. FORMATION OF ENERGY BANDS • Electrons in individual atoms can exist only at exact specified energy levels. • But the Pauli Exclusion Principle says that two electrons cannot exist in the same space at the same time. • So when we bring together billions of atoms, the electrons move their orbits ever-so-slightly, so that each one is different. • When we combine all these orbits, each different by a miniscule amount, the result is the formation of a ‘band’ of energy levels, in which an electron can exist virtually anywhere

  5. Characteristics of Energy Bands • Energy bands become wider as the distances between atoms become shorter. • The higher the energy level, the wider is the corresponding energy band that it splits into.

  6. Energy Band In Silicon • The actual band splitting in a crystal is much more complicated than shown in the figures above. • Let us consider an isolated Si atom(At. No.=14). 1s2 2s2 2p6 3s2 3p2

  7. Energy Bands at different Principal Quantum Numbers

More Related