Laser Sculpting and Processing of Silicon for Photovoltaics

Dr. Alpan Bek Center for Solar Energy Research and Applications (GÜNAM) Ankara, Turkey

By, Assoc. Prof. Dr. Alpan Bek, Center for Solar Energy Research and Applications (GÜNAM)
& Department of Physics, METU, Ankara, Turkey.

Direct writing of photonic and fluidic devices in Si by means of laser processing is of great importance as it promisses low-cost, rapid fabrication of Si devices. Although Si microfabrication techniques are well-established and technologically mature, the fabrication time and costs are still of importance as clean room environment, repetitive photomasking, mask aligning, thermal processing steps are typical requirements. Advancements in fiber laser technology has reached a stage such that high average power, nano to femtosecond pulsed lasers are reduced in dimension to about a square meter breadboard area and system costs are reduced to a fraction of a mask aligner. When integrated with galvo-, mechano-, acousto- or piezo-scanners, arbitrary 2D and 3D scan patterns of laser focus can easily be achieved. When the beam qualities are carefully selected, compatible materials can be opto-thermally proccesed in 2D and 3D. In this talk I will present sculpting of crystalline Si by 1550 nm wavelength, ns/fs pulsed fiber lasers. I will show some of our results demonstrating direct writing of holographic phase plates, microelectromechanical systems and buried channels which are fabricated by our novel laser assisted Si sculpting technique. Furthermore I will show slicing of crystal Si thin films out of bulk with the potiential for thin crystal Si solar cell fabrication, and also demonstrate direct written photonic interfaces for improved light management in silicon solar cells.
Authors: Tahir Çolakoğlu, Mona Zolfaghari Borra, Fırat İdikut, Yalın Başay, Ahmet Turnalı, Ihor Pavlov, Onur Tokel, F. Ömer Ilday, Emre Yüce, Raşit Turan, Alpan Bek.


Alpan Bek has completed his BSc and MSc studies at Bilkent University Department of Phyics. He has taken part in experimental research on optical properties of low dimensional systems and integrated optics under supervision of Prof. Atilla Aydınlı. He has obtained his PhD degree from Ecole Polytechnique Federale de Lausanne (EPFL) while he conducted his PhD work at the Max-Planck Institute for Solid State Research in Stuttgart, Germany under supervision of Prof. Klaus Kern. He has constructed an optical microscope that can resolve structures down to 5 nm with visible light. He has had a post-doctoral stay at Ludwig Maximillian’s University of Munich (LMU) in the group of Prof. Jochen Feldmann and conducted research together with Prof. Thomas Klar on plasmonic systems. Afterwards he has moved to Cluster in Biomedicine (CBM) in Trieste, Italy to work together with Dr. Marco Lazzarino on tip enhanced Raman spectroscopy (TERS). In 2011 he has returned back to Turkey as a faculty member in Physics Department of Middle East Technical University. He is currently conducting research in the fields of plasmonic solar cells and nonlinear plasmonics as the leader of the Nano-Optics Research Group and as a member of The Center for Solar Energy Research and Applications (GÜNAM).