Fundamentals of Semiconductor Physics

In recent times, crystalline semiconductors have played a major role in device fabrication for all purposes, where crystal structure plays the most crucial role. Herein, all kinds of fundamental unit cell structures have been briefly discussed, whereas Miller indices have been introduced to illustrate the orientation of the crystal structures. Basic quantum mechanics have been introduced in order to explain the fundamental properties of semiconducting materials. In this context, Sommerfeld’ free electron theory has been considered. Although this model corroborates with a few experimental observations, but can’t differentiate between semiconductors, insulators and metals. Then Kronig – Penney, which successfully explains the deviation on the basis of the band concept, has been considered. Following the Kronig – Penney model, Bloch’s theory has been introduced, and it well explains the origin of conduction and valence bands. From this concept, different types of semiconducting materials, e.g., direct and indirect band gap semiconductors, n- and p-type semiconductors, etc., have emerged. Here, properties of charge carriers, such as their charge, effective mass etc., have also been discussed. Knowing these parameters, conductivity expression and related scattering phenomena influencing conductivity have been briefly elaborated. 

Keywords: Band, Crystal structure, Fermi – Dirac statistics, Scattering, Semiconductor.