Ing Ind - Inf (Mag.)(ord. 270) - MI (486) ENGINEERING PHYSICS - INGEGNERIA FISICA

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ZZZZ

097605 - SEMICONDUCTOR NANOSTRUCTURES

097604 - PHYSICS OF SEMICONDUCTORS

097512 - PHYSICS OF SEMICONDUCTOR NANOSTRUCTURES [I.C.]

Obiettivi dell'insegnamento

The course provides a conceptual framework for understanding the essential aspects on the Physics of semiconductor devices and their limitations, as well as the Physics of low-dimensional semiconductors where quantum confinement and strain effects are exploited for tailoring electronic and optical properties.

Risultati di apprendimento attesi

- Knowledge and understanding

During the course students will learn the semiconductor structure, their fabrication and commercial aviability, the impact of defects and impurities on semiconductors properties, the new tendencies in semiconductor devices, as well as the current and upcoming applications of transparent semiconductors and oxides, the basic principle of tight-binding and k-dot-p bandstructure calculations, how to extract the main electronic and optical properties of Group IV, III-V and II-VI semiconductors from their bandstructure, understand the relevant effects of quantum confinement on the optical and electronic properties of semiconductors, understand the key elements of strain-engineering for bandstructure modification

- Apply knowledge and understanding

Numerical models implemented in MATLAB and the analysis of the working principles of devices relying on semiconductor nanostructures will be used to apply in real case studies the fundamental physical properties of semiconductor nanostructures

- Making Judgements

The students will learn which physical properties (bandgaps, effective mass, optical bandgap, band-alignment, compressive or tensile strain) are more relevant for a given application such as high mobility transitors, lasers, quantume well infrared photodetectors, resonant tunnel diodes, quantum cascade lasers.

- Lifelong learning skills

Students will gain a broad overview of the physical properties of semiconductor nanostructures and their application in microelectronics, photonics, photovoltaics and spintronics.

Defects in semiconductors Defects. Point defects: vacancies, Interstitials and substitutional atoms. Impurities. Experimental determinations. Dislocations: Burger vector, dislocation geometry (edge, screw, mixed, partial). Extended defects. Disorder. Shallow defects (Si, Ge and GaAs). Deep defects (Negative-U Center, EL2, DX). Jahn–Teller Effect. Surface charges and dipoles. Defects associated to the interfaces. Non-ideal p-n junction and metal/semiconductor interface (Schottky barrier).

Crystal structures and defects in transparent semiconductors Structure, defects and properties of transparent oxides and semiconductors (GaN, ZnO and TiO2). Amorphous films (IGZO). Current and upcoming applications: TFT transistors, displays, solar cells, etc.

Semiconductor bandstructures Bandstructure of group IV and compound (III-V, II-VI) semiconductors. Tight binding model of the bandstructure: implementation in MATLAB. The k-dot-p model: bandgap dependence of the effective mass. Symmetry of conduction (valence) band minima (maxima) and their effect on the selection rules for optical absorption: optical spin orientation. The effective mass approximation and the effective mass tensor. Density of states effective mass and conductivity effective mass. Cyclotron resonance measurements.

Semiconductors alloys Semiconductor alloys: the virtual crystal approximation. Case studies using the tight binding model implemented in MATLAB. Use of semiconductors alloys in multi-junction solar cells. Quantum confinement in semiconductor heterostructures Band offset in heterostructures, type I , II and III band alignment. Experimental determination of band offsets by X-ray photoelectron spectroscopy. Theoretical calculation of the band offset using the Jaros model. Quantum confinement effects in semiconductor heterostructures. The Schrödinger equation for the envelope function: energy levels and density of states in 2D (quantum wells), 1D (quantum wires) and 0D (quantum dots).

Strain engineering Lattice mismatch in heterostructures. Elastic strain in cubic semiconductors. Deformation potentials for hydrostatic and uniaxial strain. Strained silicon technology and strain effects on lasing in III-V and group IV semiconductors.

Prerequisiti

The student will benefit of a background knowledge of solid state Physics and quantum mechanics.

Modalità di valutazione

Students will be evaluated by means of oral examination. The oral exam is aimed at assessing the capability of the student to: -describe semiconductor structures and fabrication methods; discuss the limitations and tailoring of the semiconductors in term of defects and impurities; be aware of new applications of semiconductors, as well as of current and upcoming applications of transparent semiconductors and oxides. -discuss the effects of strain and quantum confinement, which give rise to certain optical/electronic properties and reach a good level of comprehension of fundamental physical phenomena in simplified systems.

Bibliografia

Peter Y. Yu and Manuel Cardona, Fundamentals of Semiconductors: Physics and Materials Properties, Editore: Springer, Anno edizione: 2010, ISBN: 978-3-642-00710-1
Marius Grundmann, The Physics of Semiconductors: An Introduction including Nanophysics and Applications, Editore: Springer, Anno edizione: 2010, ISBN: 978-3-642-13884-3
J. Singh, Electronic and optoelectronic properties of semiconductor structures, Editore: Cambridge, Anno edizione: 2003, ISBN: 0-521-03574-0
J. H. Davies, The physics of low-dimensional semiconductors, Editore: Cambridge, Anno edizione: 1998, ISBN: 978-0-521-48491-6

Forme didattiche

Tipo Forma Didattica

Ore di attività svolte in aula

(hh:mm)

Ore di studio autonome

(hh:mm)

Lezione

65:00

97:30

Esercitazione

35:00

52:30

Laboratorio Informatico

0:00

0:00

Laboratorio Sperimentale

0:00

0:00

Laboratorio Di Progetto

0:00

0:00

Totale

100:00

150:00

Informazioni in lingua inglese a supporto dell'internazionalizzazione

Insegnamento erogato in lingua
Inglese

Disponibilità di materiale didattico/slides in lingua inglese

Disponibilità di libri di testo/bibliografia in lingua inglese

Possibilità di sostenere l'esame in lingua inglese

Disponibilità di supporto didattico in lingua inglese