Subject: PHYSICS OF SEMICONDUCTORS (A.A. 2020/2021)
Unit Physics of Semiconductors
Microphysics and Material Structure (laboratory)
The course aims at obtaining detailed knowledge of the fundamental properties of semiconductors and of their technological applicatios
Detailed knowledge of quantum physics, statistical mechanics and elettromagnetism. The students should have the three-years Laurea completed.
Introduction: elemental and compound semiconductors. Growth techniques.
Electronic band structures: crystal structure and electronic states. Diamond and zincblende structure. Perfect crystal Hamiltonian (electronic contribution). Translation symmetry and Brillouin zones, other crystalline symmetries. Tight-binding Hamiltonian for diamond semiconductors. Example of band structures: Si, Ge and GaAs.
Semiclassical dynamics: crystal momentum, band velocity, effective mass, hole concept.
Statistics of intrinsic semiconductors: carrier density, Fermi level, Mass-action law.
Electronic properties of defects: shallow and deep impurities.
Statistics of extrinsic semiconductors: impurity levels and doping, donor and acceptor statistics, transport regimes, degenerate and compensated semiconductors, Mott transition.
Non-equilibrium semiconductors: drift and diffusion, generation and recombination processes, continuity equation, ambipolar transport, examples
Inhomogeneous semiconductors: PN junctions, Shockley equation, ideal versus real pn diodes, applications in photovoltaic solar cells and light-emitting diodes.
Semiconductor heterojunctions, metal-semiconductor junction, Schottky barrier, metal-insulator-semiconductor junctions.
Transistors: bipolar junction transistor, field effect transistors
(MESFETs, JFETs and MOSFETs).
Electronic transport: quasi classical model. Boltzmann Equation. Mobility. Scattering Mechanisms. Electron-phonon interaction. Magneto-transport. Classical and quantum Hall effect.
Frontal lectures with on screen slide presentations.
Oral exam on the topics discussed during the course. Oral exams might need to be performed in person or remotely (online) depending on the evolution of the Covid19 pandemic.
Knowledge and understanding:
After the course the student will have a detailed knowledge of the fundamental properties of semiconductors and of their technological applications.
Applying knowledge and understanding:
After the course, the student should know the structure, electronic, optical, and transport properties of the most widely used semiconductors: Si, Ge and GaAs.
After the course, the student should be able to evaluate critically experimental and theoretical results describing the most important properties of semiconductors.
The student will be able to discuss properly the problems relevant to the semiconductor properties and their technological applications.
The student will be able to learn new developments in the science and technology of semiconductors. The use of english textbooks should stimulate the learning skills and to go in deep in subjects connected with the ones presented in the lectures.
P. Yu, M. Cardona, Fundamentals of Semiconductors, Springer Verlag.
G. Grosso, G. Pastori Parravicini, Solid state physics, Academic Press, 2014.
M. Grundman, The physics of semiconductors, Springer, 2016.
S.M. Sze, K.K. Ng, Physics of Semiconductor Devices, John Wiley, 2007.
D.A. Neamen, Semiconductor Physics and Devices, Irwin, ISBN 0-256-20829-7
B. Sapoval, C. Hermann, Physics of Semiconductors, Springer Verlag.
N.W. Ascroft, N.D. Mermin, Solid State Physics, Holt-Saunders Int. Edition.