Characterization of thin film solar cell layers by x-ray based spectroscopy
X-rays interact with matter through photoabsorption, Compton scattering, and Rayleigh scattering. The strength of these interactions depend on the energy of the X-rays and the elemental composition of the material This SOPHIA webinar introduces two powerful spectroscopic tools to investigate solar cell surfaces and interfaces.
Useful information
The use of photo electron spectroscopy, using x-ray (XPS) and UV (UPS) excitation to characterize thin film solar cell components has been explored. Special emphasis is given to the determination of the chemical composition of surfaces and interfaces and on the analysis of band alignments between different layers of thin film devices by UV photo electron spectroscopy. As the HZB operates a synchrotron radiation source BESSY II which is used as a tunable X-ray source for XPS and UPS measurements, a short introduction into synchrotron radiation has also given.
Agenda
Details
Topic 1: Basics of synchrotron radiation
Speakers : HÖPFNER Britta
Synchrotron radiation can be used for various purposes. As it is a tunable X-ray source, it offers high brilliance light which can be provided polarized and in short pulses, new applications and measurement techniques where developed with its discovery. A short overview about the history and properties of synchrotron radiation will be given in this lecture
Topic 2: X-ray photo electron spectroscopy
Speakers : LAUERMANN Iver
Photo electron spectroscopy (PES), also known as x-ray photo electron spectroscopy (XPS), is a powerful surface sensitive method that is based on the emission of electrons from the sample surface due to irradiation by x-ray light. The analysis of these electrons yields information on the elemental composition of the sample surface, and the chemical environment of each element. Examples will be given for the application of XPS for the characterization of thin film solar cell components.
Topic 3: Determination of band alignments by UV photo electron spectroscopy
Speakers : CALVET Wolfram
Photo electron spectroscopy using UV light for excitation (UPS) can be utilized to examine the weakly bound electrons (valence electrons) in a sample. Since these electrons are responsible for the chemical bonds in a compound, their analysis yields important information on the chemistry of a sample. In a semiconductor, the distance between the valence band and the Fermi level can be measured using UPS. Together with the value of the band gap, this information is used to determine the band line-up in a semiconductor device like a solar cell