When 10:30 AM - 11:30 AM Feb 09, 2018
Where 1670 Beyster
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Characterizing Electronic Defects in Semiconductors & Application to Photovoltaic Devices

Professor Angus Rockett
Colorado School of Mines Department of Metallurgical and Materials Engineering

This talk reviews selected measurements we have made to characterize and understand electrically-active defects in polycrystalline thin film semiconductors.  The talk will focus primarily focusing on Cu(In,Ga)Se2 (CIGS) and related materials but also on CdTe, both of which are the key materials in high performance solar cells.  These devices are particularly relevant because they contain grain boundaries that affect the lifetime of photo-generated carriers, which tend to be lost through trapping by defects.  Selected results will be presented from a variety of characterization methods such as photomodulated admittance spectroscopy, nuclear magnetic resonance, microchemical and microstructural analysis, scanning microwave impedance microscopy, and other techniques showing how defects in the materials can be studied and their interaction with moving carriers determined.  Results of theoretical calculations showing the effect of lattice strain on defect ionization energies will also be considered.  The ways in which the results relate to both the underlying bonding and electronic structure of the material and to solar cell performance will be discussed.

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