Optics of Solid-state Nanostructures (Spring 2011)


Overview

This course focuses on semiconductor nanostructures, e.g. quantum wells (QWs) and quantum dots (QDs), and their optical properties. We will be discussing the ways in which modern crystal growth and processing techniques are used to create low-dimensional systems for the study of quantum mechanics, spin physics, and for device engineering. In addition, we will highlight optical methods for investigating these systems. The course will start by coving some fundamental concepts and build up to review state-of-the-art experiments.

The main topics to be covered include: band structure, optical absorption and emission, optical selection rules, band engineering, heterostructure growth, QWs, QDs, excitons, spin injection and polarized excitation/detection, Hanle effect, Faraday effect, dynamic nuclear polarization, optically detected magnetic resonance, paramagnetic and ferromagnetic semiconductors, spintronics and applications, and photonic band-gap devices.


Format and Requirements

The course consists of one 2-hour lecture per week and one 1-hour exercise session per week. Exercise sessions will be a forum for in depth discussion of relevant papers, assigned exercises, and general questions. A final report on an important experimental paper is required (4-5 pages or 3000-5000 words). The course will be conducted in English. The grading is pass/fail.

This course will be aimed at 3rd-year bachelor and master students in physics and nanoscience. Physics III is a prerequisite. Previous course-work in solid-state physics and quantum mechanics is expected.

Most of the source material and reading in this class will be drawn from The Physics of Low-dimensional Semiconductors, J. H. Davies (Cambridge University Press, 1998. Some reading will be based on short sections of Quantum Theory of the Optical and Electronic Properties of Semiconductors, H. Haug and S. W. Koch (World Scientific, 2009); Fundamentals of Semiconductors, P. Y. Yu and M. Cordona (Springer, 2005); Wave Mechanics Applied to Semiconductor Heterostructures, G. Bastard (Les Editions de Physique, 1988); Optical Orientation, F. Meier and B. P. Zakharchenya (North-Holland, 1984); and from original papers in scientific journals. Copies of these readings will be distributed in class.


Schedule


Lectures: Wednesdays, 14.00-16.00, Sitzungszimmer 3.12
Exercise Sessions: Thursdays, 15:00-16:00, Sitzungszimmer 3.12
Date Lecture Content
23.02.2011 Preliminary Logistics & Introduction
Course outline and expectations. What are solid-state nanostructures? Why use optics to study them? Basic concepts of quantum and statistical physics.

Exercise Session: None.

Reading: The Physics of Low-dimensional Semiconductors, chp. 1.

Downloads: Lecture slides, Exercise sheet 1.
02.03.2011 Band Structure I
Band structure. Formation of band-gaps. Conduction and valence bands. Crystal structure of common semiconductors. k·p approximation.

Exercise Session: Complete exercise sheet 1 before the session.

Reading: The Physics of Low-dimensional Semiconductors, chp. 2.

Downloads: Lecture notes, Lecture slides, Exercise sheet 1.
09.03.2011 Band Structure II
Band calculation for the III-V compound GaAs. Nearly free electron model. Kane model. Spin-orbit coupling.

Exercise Session: Complete exercise sheet 2 before the session.

Reading: The Physics of Low-dimensional Semiconductors, sec. 7.2, 7.3, 7.6, 7.8, and 10.2.

Downloads: Lecture notes.
16.03.2011 HOLIDAY
There will be no lecture this week.

Exercise Session: None.

23.03.2011 Heterostructures
Growth of heterostructures. Band engineering. Quantum wells and barriers. Doping. Strain. Wires and dots.

Exercise Session: Complete exercise sheet 3 before the session.

Reading: The Physics of Low-dimensional Semiconductors, chp. 3.

Downloads: Lecture notes, Lecture slides.
30.03.2011 Quantum Wells
Various types of quantum wells. Other low-dimensional systems. Sub-bands. Real quantum wells in heterostructures.

Exercise Session: Complete exercise sheet 4 before the session.

Reading: The Physics of Low-dimensional Semiconductors, chp. 4.

Downloads: Lecture notes, Lecture slides.
06.04.2011 Quantum Dots I (lecture by Dr. Matt Rakher)
Quantum dot (QD) theory. Band structure in QDs, density of states, optical properties, energy levels. QD growth. Experimental techniques.

Exercise Session: To be announced.

Reading: To be announced.

Downloads: Lecture notes.
13.04.2011 Optical Excitation and Selection Rules
Optical absorption. Interband absorption. Excitation with circularly polarized light. Selection rules.

Exercise Session: To be announced.

Reading: The Physics of Low-dimensional Semiconductors, chp. 8, 10; Wave Mechanics Applied to Semiconductor Heterostructures, chp. 7.

Downloads: Lecture notes, Lecture slides.
20.04.2011 Quantum Dots II (lecture by Dr. Matt Rakher)
Optical excitation in QDs. Selection rules and envelope functions. Excitons and excitonic configurations. Exchange interaction. Real measurements and experimental set-ups.

Exercise Session: To be announced.

Downloads: Lecture notes, Lecture slides.
27.04.2011 Spin State Preparation in a QD (lecture by Dr. Matt Rakher)
Discussion of two recent publications on how to optically prepare spins states in a QD. The first article deals with the preparation of an electron spin, while the second with the preparation of a hole state.

Exercise Session: To be announced.

Reading: Read Science 312, 551 (2006), and Nature 451, 441 (2008), in preparation for the class.

Downloads: Lecture slides.
04.05.2011 Optical Orientation
Electron spin precession and relaxation. The Hanle effect. The Faraday effect. Optical measurements of spin. Contact hyperfine coupling. Dynamic nuclear polarization. Optically detected magnetic resonance. Conduction band coupling to other types of localized moments.

Exercise Session: Complete exercise sheet 5 before the session.

Reading: Optical Orientation, chp. 1, 2.

Downloads: Lecture notes.
11.05.2011 Lasers and Photonic Crystals
Semiconductor laser devices and engineering. The quantum cascade laser. Waveguides, cavities, and periodic structures for photons. Photonic band-gap. Methods and applications.

Exercise Session: None.

Reading: None.

Downloads: Lecture slides.
18.05.2011 Focus: Nuclear Polarization in Quantum Dots (lecture by Dr. Matt Rakher)
Recent experiments on nuclear polarization in self-assembled quantum dots. Importance of hyperfine coupling to electron spin dynamics.

Exercise Session: None.

Reading: None.

25.05.2011 Recent Developments in Optics of Solid-state Nanostructures

Exercise Session: None.

Reading: None.

01.06.2011 Paper Presentations
Each student will present a 5-minute abstract of his/her final paper to the class. See the list of suggested publications below.



References

  • The Physics of Low-dimensional Semiconductors, J. H. Davies (Cambridge University Press, 1998).

  • Quantum Theory of the Optical and Electronic Properties of Semiconductors, H. Haug and S. W. Koch (World Scientific, 2009).

  • Fundamentals of Semiconductors, P. Y. Yu and M. Cordona (Springer, 2005).

  • Wave Mechanics Applied to Semiconductor Heterostructures, G. Bastard (Les Editions de Physique, 1988).

  • Optical Orientation, F. Meier and B. P. Zakharchenya (North-Holland, 1984).


Suggested Publications for Reports

  • Optically programmable electron spin memory using semiconductor quantum dots, M. Kroutvar et al., Nature 432, 81 (2004).