Uniform Sub-/Direct or Back Surface Laser Writing Of High And Low Spatial Frequency Surface Structures On Silicon And Its Application To Surface Enhanced Raman Spectroscopy

Date

2024-7-22

Author

İdikut, Fırat

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Material processing techniques with ultrafast lasers have been studied in recent decades. Controlling the surface morphology of processed area of the material has several benefits on nano and semiconductor technology. Processing materials with an ultrafast laser generates periodic structures under the diffraction limits, which is called Laser Induced Periodic Surface Structuring (LIPSS). The structures are formed sub/on the surface of the material. The structure formation depends on the laser wavelength, processing speed, polarization direction of the incident beam, and the fluence on the processing spot. In this thesis, two ultrafast laser sources, having 1550 nm and 1032 nm central wavelength, were used for structuring c-Si substrate to create high spatial frequency LIPSS (HSFL) and low spatial frequency LIPSS (LSFL). Direct laser writing technique was implemented into two different configurations, which are focusing the beam on the vicinity of the front surface of c-Si and focusing the beam to back surface of c-Si, coated by metal (Au, Ag or Cr). In both techniques, HSFL structures having different periods and orientations, were generated. The potential usage HSFL structures for Surface Enhanced Raman Spectroscopy was also studied for detecting molecules up to 1E-12 M.

Subject Keywords

Laser Processing, Ultrafast, Infrared, Silicon, Noble Metals, SERS, Lazerle İşleme, Ultra Hızlı, Kızılötesi, Silisyum, Noble Metals, SERS

URI

https://hdl.handle.net/11511/110831

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Graduate School of Natural and Applied Sciences, Thesis