Materials Science

1. Semiconductors and their nanostructures

1.1 Fundamental properties of semiconductors and their nanostructures.
Introduction and overview of course, basic properties of semiconductors, electronic properties of key materials (group IV and III-V semiconductors), quantum effects in semiconductor mixed crystals, epitaxial growth of multilayer materials, andsystems with varying dimensionality.
1.2 Bandstructure engineering, top down and bottom up nanofabrication.
 Bandstructure engineering, 2D systems using mixed crystals, top-down methods (lateral patterning, AFM lithography), bottom up approaches (self-assembly, CEO, patterned substrates, catalytic growth of nanowires), physical and optical characterization methods.
1.3 Doping, equilibrium and non-equilibrium carrier statistics.
Doping of semiconductors, carrier-statistics in thermal equilibrium (intrinsic, extrinsic materials), the P-N junction (band profile, built-in potential, currents flowing), examples: light emitting diodes and lasers.
1.4 Electronic structure of nanostructured semiconductor materials.
2D systems, Band offsets, alignments, experimental determination, electronic sub-bands in low dimensional systems, Schrödinger equation in heterostructures, isotropic and anisotropic effective masses, superlattices, quantum wires and quantum dots.

2. Electron transport in bulk and mesoscopic materials

2.1 Diffusive to ballistic electron transport.
Ohms Law and current density, important scattering mechanisms (ionized impurities, phonons), mobility and velocity field relationships. 2D electronic systems, modulation doping, patterning the 2D electron gas, ballistic electron transport in quantum point contacts and conductance quantization.
2.2 Magneto-transport in structured solids.
The conductivity and resistivity tensor, The classical Hall effect, Landau quantization, Shubnikov da-Haas effect, Hall effect in 2D systems, Integer quantum Hall effect, fractional quantum hall effect.
2.3 Tunneling transport through potential barriers.
Electron incident on a single heterointerface, the transfer matrix method, rectangular barrier, the WKB-approximation to calculate the tunneling rate, double barrier resonant tunneling diode
2.4 Electronic transport in mesoscopic devices
Coulomb energy and temperature, Coulomb blockade, Single electron switching devices, charge stability diagram, the single electron transistor (SET), Nanowire SET, few electron artificial atoms. Double Q-Dots, measuring / manipulating single charges and their spins.

3. Optical properties of engineered solids

3.1 Introduction to optical properties of materials
Optical coefficients, electrons in an electromagnetic field, interband transitions in solids, absorption spectrum and joint density of states, interband luminescence, excitonic effects in inorganic and organic materials.
3.2 Optical properties of quantum wires and dots
Inter-band optical transitions in quantum wells (parity and polarization selection rules), interband luminescence in solids, Inter-subband transitions in quantum wells, mid infrared emitters and detectors, optical properties of quantum dots, single photon emitters and quantum cryptography.

4. Carbon based nano-materials

4.1 Graphene and Carbon Nanotubes
  Graphene (crystal and electronic structure), carbon nanotubes (CNTs), wavevector quantization and electronic structure, metallic and semiconducting CNTs, methods of CNT synthesis, measuring electronic structure, quantized conductance in your living room, graphene=material of the future ? Diamond, color centers and the magical NV- center.

5. Quantum emitters and structured nanophotonic materials

5.1 Quantum engineered light emitting devices
Spontaneous vs. stimulated emission, carrier recombination (radiative vs. non-radiative), LEDs, enhancing light extraction efficiency, lasers (need for, design elements, gain spectrum, condition for self-sustaining laser oscillation, transparency) influence of dimensionality on laser performance.
5.2 Photonic crystals
The concept of a “photonic crystal”, photonic bandstructure, fabrication methods for 3D and 2D photonic crystals, defects to localize and trap light, integrated optical devices, photonic crystal fibers.
5.3 Controlling the light-matter interaction
Photonic nanostructures, optical resonators, quantization of the electromagnetic field in a cavity, the Purcell effect, new generations of quantum light emitter and ultra-efficient nano-lasers of the future.

Die Vorlesung wird kompakt in der ersten Hälfte der Vorlesungszeit gelesen. Die Vorlesung wird ergänzt durch Tutorübungen.

The learning outcome is tested in an oral exam. Participation in tutorials is strongly recommended.