Semiconductor Synthesis and Nanoanalytics

This MSc level lecture focuses on advanced methods for the synthesis of semiconductor thin films and for characterization of their properties. A wide range of modern technological devices rely on thin film semiconductors possessing highly controlled composition, structure, and nanoscale morphology. This module will introduce students to the physical principles and experimental realization of the most important methods employed today for deposition and characterization of such materials.

During the first half of the semester, the following deposition methods will be addressed in detail:

• Molecular beam epitaxy (MBE)
• Reactive sputtering
• Chemical vapor deposition (CVD)
• Atomic layer deposition (ALD)

Energetic and kinetic considerations associated with different growth modes will be introduced. Along the way, the physics of plasmas for semiconductor synthesis; high vaccum technologies and gas delivery systems; nucleation, growth, strain, and surface diffusion; and surface chemical reaction kinetics will be discussed. 

During the second half of the semester, the following nanoanalytical methods will be specifically introduced:

• Imaging methods: scanning probe microscopy methods, electron microscopy methods, Kelvin probe force microscopy
• Structural characterization methods: X-ray diffraction, low energy electron diffraction, reflection high energy electron diffraction
• Elemental analysis: X-ray photoelectron spectroscopy, Auger electron spectroscopy, energy dispersive X-ray spectroscopy, secondary ion mass spectrometry
• Vibrational spectroscopy: Fourier transform infrared spectroscopy, Raman spectroscopy
• Optical spectroscopy: variable angle spectroscopic ellipsometry, absorption spectroscopy, photoluminescence spectroscopy
• Electronic transport measurements

After successful completion of this module the students will possess a basic knowledge of all synthesis and nanoanalytical methods discussed, including their physical foundations and their state-of-the-art experimental realization. This will provide them with the necessary knowledge to effectively use these methods in their later studies (e.g. Bachelor or Master Theses) and to interpret obtained experimental results correctly and critically. After successful completion of this module, the student is able to:

• understand the key advantages, limitations, characteristics of the different synthesis methods in terms of key semiconductor properties
• describe modern implementations of each synthesis method
• understand the physics of plasma-assisted syntheses
• understand how key experimental parameters (e.g. temperature, pressure, flux, bias) affect the growth modes and properties of semiconductor films and nanostructures
• describe the physical foundations, key information that is obtained, and the state-of-the-art applications of the nanoanalytical methods discussed
• interpret experimental results correctly and critically
• explain the physical principles and interactions upon which each experimental method is based
• recognize how different methods complement one another
• describe limitations of different methods in terms of sensitivity, resolution, and impact on investigated samples

no requirements beyond the admission to the Physics Master's programme.

The modul consists of a lecture and exercise classes.

Lecture: In classroom lectures, the teaching and learning content is presented and explained in a didactical, structured, and comprehensive form. This content includes basic knowledge, as well as selected current topics in evolving areas of solid state spectroscopy. Practical and modern aspects of solid state spectroscopy are highlighted in terms of the physical principles upon which they are built. Crucial facts are conveyed by involving the students in scientific discussions to develop their intellectual power and to stimulate their analytic thinking on physics problems. Regular attendance of the lectures is therefore highly recommended.

Exercise: The presentation of the learning content is enhanced by optional supplemental lectures, laboratory tours, and guest presentations that place the lecture content in the context of modern experimental solid state physics research. These learning activities are intended to deepen the students’ understanding and to help their learning of the course material.

Lecture notes are written using a tablet and are complemented by powerpoint slides that provide figures and videos representing modern research examples, schematic illustrations, and representative data.

• H. Kuzmany: Solid State Spectroscopy, Springer-Verlag, (2009)
• I. Pelant & J. Valenta: Luminescence Sspectroscopy of Semiconductors, Oxford University Press, (2012)
• M. Ohring: Materials Science of Thin Films, Academic Press (Elsevier), (2002)
• T. Kaariainen, D. Cameron, M.-L. Kaariainen, A. Sherman, Atomic Layer Deposition: Principles, Characteristics, and Nanotechnology Applications, Wiley, (2013)

There will be an oral exam of 25 minutes duration. Therein the achievement of the competencies given in section learning outcome is tested exemplarily at least to the given cognition level using comprehension questions and sample calculations.

For example an assignment in the exam might be:

• Describe of the potential distribution and plasma composition across a DC glow discharge
• What are the energetic considerations that define the stability regions for the three major film growth modes?
• Explain the major extended defect types in epitaxial thin films and the consequences they can have on optoelectronic properties of the resulting materials.
• Describe the different steps associated with an atomic layer deposition cycle and explain the different factors that affect growth rate.
• Describe and explain the electronic transitions associated with different X-ray and electron spectroscopies
• Explain the selection rules for vibrational spectroscopies and provide examples of active and inactive modes
• Explain what the experimentalist can learn from different X-ray diffraction modes and geometries
• Describe the different radiative and non-radiative recombination mechanisms in a semiconductor