University of Freiburg

Institute of Physics

Experimental Atomic and Molecular Physics and Cold Chemistry

hanan.mir(at)physik.uni-freiburg.de

Pump-probe studies of transient phenomena in the laser processing of silicon carbide

Silicon carbide (SiC) is a wide-band-gap semiconductor material which is perfectly suited to power electronics applications. SiC-based power electronics are particularly relevant for the transformation of our global energy system, e.g. for use in solar inverters and in electric vehicles, and are therefore, in line with the research objectives of the Fraunhofer Institute for Solar Energy Systems ISE. In comparison to silicon wafers, single crystal SiC wafers are very expensive and improved technologies for wafer manufacturing are of great commercial interest. Laser processing for innovating additive micromachining (e.g., annealing, contact formation) and destructive micromachining (e.g., milling, polishing, dicing, ablation) is of particular relevance, because it is inexpensive, material saving and energy efficient.

This research project, which is based at Fraunhofer ISE, deals with the laser-based characterization of SiC wafers and the development of laser-based techniques for SiC laser process monitoring. An extension of an existing experimental setup for pump-probe microscopy (shown in the figure below) [1, 2] will be used to study intrinsic and laser-induced defects in SiC, to identify dominant nonlinear absorption phenomena and to unravel the dynamics of laser-induced stress. The use of complementary static characterization techniques, including photoluminescence and Raman spectroscopy, is also envisaged.

Supervisor: Katrin Erath

Pump-probe setup at Fraunhofer ISE

References:

[1] F. Meyer, M. Böhler, A. A. Brand, and J. F. Nekarda, „Automated pump-probe microscope to observe laser ablation on a picosecond scale“, Proc. SPIE 11056, Optical Measurement Systems for Industrial Inspection XI, 110561V (2019); https://doi.org/10.1117/12.2525709

[2] F. Meyer, A. Büchler, A. A. Brand, M. K. Dasa, J. F. Nekarda, and R. Preu, „Impact of solidification dynamics on crystal properties of silicon molten by a nanosecond laser pulse“, Appl. Phys. A 124, 254 (2018); https://doi.org/10.1007/s00339-018-1682-6