SEMICONDUCTOR PHYSICS AND TECHNOLOGYAcademic Year 2022/2023 - Teacher: SALVATORE MIRABELLA
Expected Learning Outcomes
Aim of this course is to provide students with advanced knowledge of Physics of semiconductor materials and related technologies.
For what concerns the above subjects of Physics and Technologies of semiconductors, the course will promote the following skills:
- knowledge and understanding. Critical understanding of the most advanced developments of Modern Physics, both theoretical and experimental, and their interrelations, also across different subjects. Adequate knowledge of advanced mathematical and numerical tools, currently used in both basic and applied research. Remarkable acquaintance with the scientific method, understanding of nature, and of the research in Physics.
- applying knowledge and understanding. Ability to identify the essential elements in a phenomenon, in terms of orders of magnitude and approximation level, and being able to perform the required approximations. Ability to use analogy as a tool to apply known solutions to new problems (problem solving). Ability to plan and apply experimental and theoretical procedures to solve problems in academic or applied research, or to improve existing results.
- making judgements. Ability to work with increasing level of independence, also undertaking responsibility in planning and managing projects. Ability to convey own interpretations of physical phenomena, when discussing within a research team. Developing one's own sense of responsibility, through the choice of optional courses and of the final project.
- communication skills. Ability to discuss about advanced physical concepts, both in Italian and in English. Ability to present one's own research activity or a review topic both to an expert and to an non-expert audience.
- learning skills. Ability to acquire adequate tools for the continuous update of one's knowledge. Ability to access to specialized literature both in the specific field of one's expertise, and in closely related fields. Ability to exploit databases and bibliographical and scientific resources to extract information and suggestions to better frame and develop one's study and research activity.
Lectures (LIM slides available). Seminars.
Visit to research labs at DFA.
Should the circumstances require online or blended teaching, appropriate modifications to what is hereby stated may be introduced, in order to achieve the main objectives of the course.
Exams may take place online, depending on circumstances.
IMPORTANT: basic knowledge of Condensed Matter Physics
IMPORTANT: basic knowledge of Quantum Mechanics
USEFUL: basic knowledge of Statistical Mechanics
Attendance of LessonsAttendance to the course is usually compulsory (consult the Academic Regulations of the Course of Studies)
Detailed Course Content
- Band structures and doping
Semiconductor structure and general properties - Bandgap formation - Energy band structure – Metals, insulators and semiconductors
Density of states and effective mass - Electons and Holes
Intrinsic semiconductor statistics - Mass action law - Acceptor and donors - Charge neutrality
Doped semiconductor statistics - Doping compensation - Thermal dependance of carrier density
- Electrical and optical properties
Conductance, scattering, mobility and thermal dependance - Einstein relation
Generation and recombination processes - Band-to-band recombination - Shockley, Read & Hall recombination - Experimental determination of carrier density and their mobility - Haynes Shockley experience
Free carrier absorption - Direct optical transition
Indirect optical absorption - Excitons - Light emission – Binary, ternary and quaternary semiconductors - Optical properties of heterostuctures and nanostructures
- Simple devices
Metal/oxide/semicondutors systems - MOS capacitance - Flat band voltage
pn junction at equilibrium: band bending, depletion region, internal electric field
pn junction out of equilibrium: direct and inverse polarization, minority charge carriers injection and extraction, Shockley law: IV curve
pn junction: quasi Fermi level, CV curve, jnuction breakdown, transient behavior
Metal-oxide-semiconductor field-effect transistor (MOSFET)
- Semiconductor technologies
Moore Law, Lithography, Ion implantation, Thermal diffusion
SiC and power devices
Semiconductor sensors (definition, properties, mechanisms and nanostructures advantages). Semiconductor/gas interface: surface states, adsorption, chemoresistive effects.
Gas sensors based on semiconductors: adsorption kinetics, response times. UV sensors.
Semiconductor/liquid interface: Electrochemical cells, redox reactions, Nernst Equation, reference electrodes, electrical double layer.
Electrochemical techniques applied to semiconductors: ciclic and transient voltammetry, EIS (electrochemical impedance spectroscopy)
B. Sapoval, C. Hermann - Physics of Semiconductors - Springer-Verlag
S.M. Sze - Physics of Semiconductor Devices (3rd edition) - Wiley
L. Colombo - Fisica dei semiconduttori - Zanichelli
K. B. Oldham, J. C. Myland - Fundamentals of Electrochemical Science - Academic Press
|1||Energy band structure- doping- Charge carriers statistics (10 hours)||Ch. 1-4 Sapoval Hermann|
|2||Electrical charge transport- light absorption and radiation (10 hours)||Ch. 5-7 Sapoval Hermann|
|3||Shottky junctions, MOS, pn junctions, MOSFET (10 hours)||Ch. 8-10 Sapoval Hermann, Ch.2-7 Sze|
|4||Technologies for semiconductor devices(6 hours)||Ch. 10 Sapoval Hermann|
|5||Gas/semiconductor and liquid/semiconductor interfaces (10 hours)||Ch. 5-9 Oldham|
Learning Assessment ProceduresOral interview (3-4 questions). Slide support or monographic thesis (5-10 pages) are allowed.
Examples of frequently asked questions and / or exercises
Following questions are examples and do not represent an exhaustive list
Charge carriers statistics in doped semiconductors
Light absorption by free carriers
Gas sensor based on semiconductors - gas/semiconductor interface
Electrochemical sensors - liquid/semiconductor interfaces