3d-microstructuring of silicon induced by nanosecond pulsed infrared fiber laser for potential solar cell applications

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2022-9-02
BÜLBÜL TATBUL, BESNA
Laser-induced three-dimensional (3D) structuring of silicon is a highly desired technology as silicon drives the semiconductor industry with its wide range of applications in solar cells, telecommunications, microelectronics, integrated photonics, etc. Structuring of silicon for such applications is typically performed by lithographic pattern production and pattern transfer via plasma etching, reactive ion etching, or chemical etching. However, conventional lithography methods are limited to the surface of the silicon and do not allow direct fabrication of 3D structures buried deep inside the silicon. Novel laser-based methods are emerging to fabricate 3D subsurface functional elements in silicon. The 3D structuring of silicon by laser requires high peak intensity, short-pulsed lasers that can induce modification in the silicon by exploiting nonlinear photon absorption. Until recently, laser-induced subsurface modification of the silicon without damaging the surface had been unsuccessful. In this thesis, highly controlled surface and subsurface modifications are presented in crystalline silicon (c-Si) using a custom-built nanosecond pulsed infrared laser. To reveal true 3D structures, laser-modified parts are etched in a highly selective chemical solution. Our novel approach is successfully implemented to fabricate 3D microhole arrays inside the c-Si wafer, and 3D micropillar arrays on the surface of the c-Si wafer, for potential applications in transparent solar cells and radial junction photovoltaics, respectively. Since our method does not require mask copying, it offers fewer processing steps than traditional lithographic methods and can be easily adjusted to different applications.

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Citation Formats
B. BÜLBÜL TATBUL, “3d-microstructuring of silicon induced by nanosecond pulsed infrared fiber laser for potential solar cell applications,” M.S. - Master of Science, Middle East Technical University, 2022.