Semiconductor physics

A.Y. 2020/2021
Overall hours
Learning objectives
The course provides fundamentals for the understanding of the microscopic properties of relevant topics of Physics of Semiconductors and of their applications. Special focus will be given on:
1.Understanding the electronic, vibrational, optical and magnetic properties of semiconductors
2.Defects (shallow and deep)
3.Transport in 3D semiconductors
4.Electronic properties and transport in nanostructures 2D, 1D, 0D
5.Physics of heterostructures and junctions: basic concepts for understanding nanoelectronic devices
Expected learning outcomes
Skills acquired by the student at the end of the course:
1. Description of microscopic mechanisms responsible of transport properties in semiconductors
2. Knowledge of main growth and characterization techniques used for semiconductors
3. Knowledge of principal computational techniques used for semiconductors
4. Description of quantum confinement effects in semiconductor nanostructures.
5. Knowledge of main processes governing the physics of semiconductors. Application of skills acquired in the course to made research and development of semiconductor technology in academy or in industry.
Course syllabus and organization

Single session

Lesson period
First semester
The course will be delivered entirely remotely in case of travel
restrictions due to Covid-19. In this case, the lectures will be offered
preferably in virtual classrooms (zoom platform) in synchronous connection, with the possibility of real-time interaction between the students and the teacher.
Course syllabus
Purpose of the course is the illustration of basic concepts of Physics of Semiconductors. During the class the main simulation methods and experimental techniques for the study of the semiconductor physics will be introduced; the industrial applications and recent development of new materials for ultra-scaled electronics will be mentioned.

1. Introduction to growth techniques for semiconductors(2)
MOCVD, MBE, ALD techniques.
2. Crystal structures (1)
Crystal structures; Bravais lattices; spatial point groups; reciprocal lattice; Miller indexes.
3. Energy bands (4)
Bloch states; Wannier functions; tight binding method; pseudo-potential techniques; kp approximation; valence and conduction bands; definition of effective mass and its experimental measurement.
4. Phonons and thermal properties (3)
Phonon branches; theoretical models; experimental techniques.
5. Defects in semiconductors: structural, electronic and vibrational properties (4)
Point defects; doping agents; impurities; complexes. Shallow defects: effective mass theory. Deep defects: Green functions.
6. Equilibrium distribution (4)
Statistics; thermodynamics; density of states; electron and hole distribution; intrinsic and extrinsic semiconductors; Fermi level; chemical potential.
7. Optical properties (4)
Electron-photon interaction: polaritons. Infra-band absorption, inter-band absorption; excitons, free-carrier absorption. Reflectivity. Kramers-Kronig relations. Photon scattering: Raman spectroscopy. Photoluminescence. Photo-ionization.
8. Transport properties (4)
Macroscopic quantities. Boltzmann equation; distribution function; charge transport; scattering processes, relaxation time; Hall effect; magneto-resistance; high field effects; hot carriers, Gunn effect.
9. Excess carriers (2)
Generation and recombination. Drift and diffusion. Thermodynamic equilibrium junctions. Non-equilibrium junctions.
10. Berry phase (2). Polarization in semiconductors.
11. Heterostructures (4)
Space charge region; impact ionization; tunnel effect; two dimensional electron gas. Transport. Quantum Hall effect.
12. Solar Cells (2)
Photovoltaic effect; solar cell efficiency; solar cells of first, second, and third generation; commercial issues.
13. Nanostructures. (2)
Quantum well. 1D e 0D structures; Coulomb blockade. Single electron devices.
14. Spintronics. (2)
Introduction to spin electronic. Rashba effect; spin transistor; magnetic semiconductors; Heusler compounds.
15. Quantum computer. (2)
Proposals for a quantum computer; Kane's architecture
Prerequisites for admission
Basic notions of quantum mechanics and of structure of matter
Teaching methods
During the oral lesson the topics are illustrated also by examples and discussions to provide a deep knowledge of the more relevant ideas an methods
Teaching Resources
Lectures notes. M.Balkanski and R.F.Wallis, Semiconductor Physics and applications, (Oxford University Press, 2000); P.Yu and M. Cardona Fundamentals of Semiconductors (Springer 2010). References about specific topics can be provided during the lessons.
Assessment methods and Criteria
During the oral exam (duration about 30-40 min.) the student illustrates the topics of the program. Particular weight is assigned to the understanding of ideas and methods relevant for the study of the physical properties of semiconductors
FIS/03 - PHYSICS OF MATTER - University credits: 6
Lessons: 42 hours
Professor: Debernardi Alberto