Starting from 1st Fabruary 2015 SOPHi@webinar platform has been moved to CHEETAH webinar platform
in date 23/05/2014

Characterization of thin film solar cell layers by x-ray based spectroscopy

CISSY_XPS_UPSX-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.



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