Effect of surface texturization by 1064 nm - nanosecond pulsed fiber laser on optical reflection and absorption of single crystal silicon

Single crystal n-type silicon wafer with (100)-orientation was texturized by using nanosecond pulsed, Ytterbium doped fiber laser with the master oscillator power amplifier architecture (MOPA), operating at the peak wavelength of 1064 nm. All texturing processes were done with the repetition frequency range of 40 – 100 kHz, the scanning speed range of 50 – 2000 mm/s and at the average laser powers of 10, 15 and 20 W. In this study, focused spot size and laser pulse width were not changed. The normal incidence reflectivity of the samples produced at different laser texturize parameters was measured by using Fourier transform reflection and conventional optical reflection methods. For the electrical measurements, coplanar aluminum contacts were evaporated on the texturized samples. The wavelength dependent absorption coefficient of the samples was measured in Fourier Transform Photoconductivity Spectroscopy (FTPS). The surface morphologies of texturized samples were observed with scanning electron microscopy (SEM). By using the results, it's been concluded that, the reflectivity of the single crystal samples can be reduced significantly and the absorption coefficient is increased reasonably by nano-second pulsed fiber laser operating at1064 nm. The results were also discussed under, especially the concept of overlap of the focused laser beam and the scan speed.