scholarly journals Micro/Nano Amorphization/Oxidation Of Silicon Induced By High Repetition Femtosecond Laser Pulses

2021 ◽  
Author(s):  
Amirkianoosh Kiani
Keyword(s):  
Solar Cell ◽  
Femtosecond Laser ◽  
Surface Temperature ◽  
Pulse Duration ◽  
Analytical Model ◽  
Repetition Rate ◽  
Crystalline Silicon ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Laser Parameters

The main aim of this thesis is to develop a new method for direct micro/nano amorphization/oxidation of silicon using femtosecond laser irradiation and its applications in maskless lithography and solar cell fabrication. Amorphization and oxidation occur when crystalline silicon is exposed to the irradiation of femtosecond laser pulses below the ablation threshold. Mechanisms of morphization and oxidation were discussed and the surface temperature model was developed to study the relation between laser parameters and observed amorphization and oxidation. A systematic theoretical and experimental study of the influence of the laser parameters on the quality of amorphorized area and the size of the feature fabricated through amorphization has been studied. It was found that during the process of silicon amorphization and oxidation, the higher repetition rate of laser pulses yields smooth morphology with better repeatability. Increasing pulse duration and number of pulses were seen to increase the line width. However, increasing the number of pulses does not result in ablation of the target area. An analytical model was developed for the calculation of the average surface temperature after n-pulses. The effect of the laser pulse width was investigated by developing an analytical model for the calculation of the non-dimensional surface temperature with various pulse widths. It was found from experimental and analytical results that for a constant power and repetition rate, an increase in the pulse duration corresponds to a significant increase in the surface temperature. It results in an increase in the amount of modified material as well as improvement of light absorption in the case of amorphization. The main aim of this thesis is to develop a new method for direct micro/nano amorphization/oxidation of silicon using femtosecond laser irradiation and its applications in maskless lithography and solar cell fabrication.Amorphization and oxidation occur when crystalline silicon is exposed to the irradiation of femtosecond laser pulses below the ablation threshold. Mechanisms of morphization and oxidation were discussed and the surface temperature model was developed to study the relation between laser parameters and observed amorphization and oxidation. A systematic theoretical and experimental study of the influence of the laser parameters on the quality of amorphorized area and the size of the feature fabricated through amorphization has been studied. It was found that during the process of silicon amorphization and oxidation, the higher repetition rate of laser pulses yields smooth morphology with better repeatability. Increasing pulse duration and number of pulses were seen to increase the line width. However, increasing the number of pulses does not result in ablation of the target area. An analytical model was developed for the calculation of the average surface temperature after n-pulses.The effect of the laser pulse width was investigated by developing an analytical model for the calculation of the non-dimensional surface temperature with various pulse widths. It was found from experimental and analytical results that for a constant power and repetition rate, an increase in the pulse duration corresponds to a significant increase in the surface temperature. It results in an increase in the amount of modified material as well as improvement of light absorption in the case of amorphization.The amorphous silicon and silicon oxide can act as an etch stop. Therefore, maskless lithography iis possible with the direct patterning (amorphization and oxidation) of crystalline silicon. Experimental results have proved the feasibility of the proposed concepts. The thin-film of amorphous silicon generated on the silicon substrate has a potential for use in photovoltaic devices and solar cell fabrication. In comparison with previous methods, the direct oxidation/amorphization of silicon induced by the femtosecond laser is a maskless single-step technique which offers a higher flexibility and reduced processing time.

scholarly journals Micro/Nano Amorphization/Oxidation Of Silicon Induced By High Repetition Femtosecond Laser Pulses

2021 ◽  
Author(s):  
Amirkianoosh Kiani
Keyword(s):  
Solar Cell ◽  
Femtosecond Laser ◽  
Surface Temperature ◽  
Pulse Duration ◽  
Analytical Model ◽  
Repetition Rate ◽  
Crystalline Silicon ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Laser Parameters

The main aim of this thesis is to develop a new method for direct micro/nano amorphization/oxidation of silicon using femtosecond laser irradiation and its applications in maskless lithography and solar cell fabrication. Amorphization and oxidation occur when crystalline silicon is exposed to the irradiation of femtosecond laser pulses below the ablation threshold. Mechanisms of morphization and oxidation were discussed and the surface temperature model was developed to study the relation between laser parameters and observed amorphization and oxidation. A systematic theoretical and experimental study of the influence of the laser parameters on the quality of amorphorized area and the size of the feature fabricated through amorphization has been studied. It was found that during the process of silicon amorphization and oxidation, the higher repetition rate of laser pulses yields smooth morphology with better repeatability. Increasing pulse duration and number of pulses were seen to increase the line width. However, increasing the number of pulses does not result in ablation of the target area. An analytical model was developed for the calculation of the average surface temperature after n-pulses. The effect of the laser pulse width was investigated by developing an analytical model for the calculation of the non-dimensional surface temperature with various pulse widths. It was found from experimental and analytical results that for a constant power and repetition rate, an increase in the pulse duration corresponds to a significant increase in the surface temperature. It results in an increase in the amount of modified material as well as improvement of light absorption in the case of amorphization. The main aim of this thesis is to develop a new method for direct micro/nano amorphization/oxidation of silicon using femtosecond laser irradiation and its applications in maskless lithography and solar cell fabrication.Amorphization and oxidation occur when crystalline silicon is exposed to the irradiation of femtosecond laser pulses below the ablation threshold. Mechanisms of morphization and oxidation were discussed and the surface temperature model was developed to study the relation between laser parameters and observed amorphization and oxidation. A systematic theoretical and experimental study of the influence of the laser parameters on the quality of amorphorized area and the size of the feature fabricated through amorphization has been studied. It was found that during the process of silicon amorphization and oxidation, the higher repetition rate of laser pulses yields smooth morphology with better repeatability. Increasing pulse duration and number of pulses were seen to increase the line width. However, increasing the number of pulses does not result in ablation of the target area. An analytical model was developed for the calculation of the average surface temperature after n-pulses.The effect of the laser pulse width was investigated by developing an analytical model for the calculation of the non-dimensional surface temperature with various pulse widths. It was found from experimental and analytical results that for a constant power and repetition rate, an increase in the pulse duration corresponds to a significant increase in the surface temperature. It results in an increase in the amount of modified material as well as improvement of light absorption in the case of amorphization.The amorphous silicon and silicon oxide can act as an etch stop. Therefore, maskless lithography iis possible with the direct patterning (amorphization and oxidation) of crystalline silicon. Experimental results have proved the feasibility of the proposed concepts. The thin-film of amorphous silicon generated on the silicon substrate has a potential for use in photovoltaic devices and solar cell fabrication. In comparison with previous methods, the direct oxidation/amorphization of silicon induced by the femtosecond laser is a maskless single-step technique which offers a higher flexibility and reduced processing time.

Structural and optical property tailoring of black silicon with fs-laser pulses

2012 ◽  
Vol 1405 ◽  
Author(s):  
S. Kontermann ◽  
A. L. Baumann ◽  
T. Gimpel ◽  
K.M. Guenther ◽  
A. Ruibys ◽  
...  
Keyword(s):  
Solar Cell ◽  
Femtosecond Laser ◽  
Band Gap ◽  
Silicon Solar Cell ◽  
Crystalline Silicon ◽  
Thick Layer ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Black Silicon ◽  
Material Characteristics

ABSTRACTIrradiating a planar silicon surface with femtosecond laser pulses under a sulfuric atmosphere creates first a structured surface featuring cones of up to 20 microns in height, and second a 0.1 – 1 μ m thick layer of multi-crystalline silicon on theses cones containing up to 1 at.% sulfur acting as n-type dopant. Further, the sulfur establishes energy states within the band gap of silicon allowing for the absorption of infrared (IR) light with energies below the band gap energy of silicon. This black silicon process is distinguished by the fact that only one single laser process is required to tailor three material characteristics in on step: the surface structure, the doping and the light absorption. In this work we study structural and optical material characteristics of black silicon. For the first time this work presents properties of black silicon processed with shaped femtosecond laser pulses. Finally, black silicon substrate is used as substrate for manufacturing a black silicon solar cell with a femtosecond laser pulse formed sulfur emitter. For such a black silicon solar cell we achieved a record efficiency of η =4.5%

Optical breakdown and filamentation of femtosecond laser pulses propagating in air at a kHz repetition rate

2004 ◽  
Vol 13 (3) ◽  
pp. 359-363 ◽  
Author(s):  
Duan Zuo-Liang ◽  
Chen Jian-Ping ◽  
Li Ru-Xin ◽  
Lin Li-Huang ◽  
Xu Zhi-Zhan
Keyword(s):  
Femtosecond Laser ◽  
Repetition Rate ◽  
Optical Breakdown ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses

scholarly journals High-Repetition-Rate Femtosecond Laser Processing of Acrylic Intra-Ocular Lenses

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 242 ◽  
Author(s):  
Daniel Sola ◽  
Rafael Cases
Keyword(s):  
Femtosecond Laser ◽  
Repetition Rate ◽  
Laser Processing ◽  
Refractive Index Change ◽  
Laser Pulses ◽  
Processing Parameters ◽  
High Repetition Rate ◽  
Femtosecond Laser Pulses ◽  
Periodic Patterns ◽  
High Repetition

The study of laser processing of acrylic intra-ocular lenses (IOL) by using femtosecond laser pulses delivered at high-repetition rate is presented in this work. An ultra-compact air-cooled femtosecond diode laser (HighQ2-SHG, Spectra-Physics) delivering 250 fs laser pulses at the fixed wavelength of 520 nm with a repetition rate of 63 MHz was used to process the samples. Laser inscription of linear periodic patterns on the surface and inside the acrylic substrates was studied as a function of the processing parameters as well as the optical absorption characteristics of the sample. Scanning Electron Microscopy (SEM) Energy Dispersive X-ray Spectroscopy (EDX), and micro-Raman Spectroscopy were used to evaluate the compositional and microstructural changes induced by the laser radiation in the processed areas. Diffractive characterization was used to assess 1st-order efficiency and the refractive index change.

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