Silicon Surface Morphologies after Femtosecond Laser Irradiation

Tull, Brian R.; Carey, James E.; Mazur, Eric; McDonald, Joel P.; Yalisove, S. M.

doi:10.1557/mrs2006.160

Cited by 165 publications

(115 citation statements)

References 84 publications

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“…Generally, higher fluence was necessary to generate larger internal ablation pressure to delaminate and lift thicker films, but at the cost of creating larger diameter craters in the c-Si substrate. The observed fluence thresholds and the ablation crater diameters were nearly identical in SiO x films in comparison with SiN x films of the same thickness, and are in accord with the results reported for 147 nm SiO x films [13]. During KOH etching, the smallest ablation craters in 100 nm thick SiN x /SiO x films did not etch to form inverted-pyramids.…”

Section: Optimization Of the Texturing Processsupporting

confidence: 88%

“…The technique enables inverted-pyramidal texturing of Si with flexible pattern designs, thus exploiting the low reflection, high diffractive light-trapping capability and passivation benefits of such texture. While femtosecond lasers have been used to texturize c-Si with chemical assistance [13], the produced 'black' silicon has significant structural damage that prevents passivation and decreases carrier lifetime. Alternatively, femtosecond lasers have been applied to SiO x thin films on c-Si to form micro-blisters [13,14] and induce catapulting which we extend to SiN x and further exploit here to form a high resolution hard mask for KOH etching.…”

Section: Introductionmentioning

confidence: 99%

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Ultrafast laser direct hard-mask writing for high efficiency c-Si texture designs

et al. 2013

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This study reports a high-resolution hard-mask laser writing technique to facilitate the selective etching of crystalline silicon (c-Si) into an inverted-pyramidal texture with feature size and periodicity on the order of the wavelength which, thus, provides for both anti-reflection and effective light-trapping of infrared and visible light. The process also enables engineered positional placement of the invertedpyramid thereby providing another parameter for optimal design of an optically efficient pattern. The proposed technique, a non-cleanroom process, is scalable for large area micro-fabrication of high-efficiency thin c-Si photovoltaics. Optical wave simulations suggest the fabricated textured surface with 1.3 μm inverted-pyramids and a single anti-reflective coating increases the relative energy conversion efficiency by 11% compared to the PERL-cell texture with 9 μm inverted pyramids on a 400 μm thick wafer. This efficiency gain is anticipated to improve further for thinner wafers due to enhanced diffractive light trapping effects.

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Section: Optimization Of the Texturing Processsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Ultrafast laser direct hard-mask writing for high efficiency c-Si texture designs

et al. 2013

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“…2. It is suggested that growth is a dominant spike formation mechanism under nanosecond laser while ablation is dominant for femtosecond pulses [11].…”

Section: Surface Topography On Laser Irradiated A-si:hmentioning

confidence: 99%

“…Extensive work on surface texturing of crystalline bulk silicon had been reported by using both femtosecond and nanosecond laser [11,12]. Wang et al [13,14] and Nayak and Gupta [9] also achieved both surface texturing and crystallization on a-Si:H thin films by using femtosecond laser.…”

Section: Introductionmentioning

confidence: 99%

Effect of hydrogen on surface texturing and crystallization of a-Si:H thin film irradiated by excimer laser

2012

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Hydrogenated amorphous silicon (a-Si:H) thin films have been considered for use in solar cell applications because of their significantly reduced cost compared to crystalline bulk silicon. However, their overall efficiency and stability are lower than that of their bulk crystalline counterpart. Limited work has been performed on simultaneously solving the efficiency and stability issues of a-Si:H. Previous work has shown that surface texturing and crystallization on a-Si:H thin film can be achieved through a single-step laser processing, which can potentially alleviate the disadvantages of a-Si:H in solar cell applications. In this study, hydrogenated and dehydrogenated amorphous silicon thin films deposited on glass substrates were irradiated by KrF excimer laser pulses and the effect of hydrogen on surface morphologies and microstructures is discussed. Sharp spikes are focused only on hydrogenated films, and the large-grained and fine-grained regions caused by two crystallization processes are also induced by presence of hydrogen. Enhanced light absorptance is observed due to light trapping based on surface geometry changes of a-Si:H films, while the formation of a mixture of nanocrystalline silicon and original amorphous silicon after crystallization suggests that the overall material stability can potentially improve. The relationship between crystallinity, fluence and number of pulses is also investigated. Furthermore, a step-by-step crystallization process is introduced to prevent the hydrogen from diffusing out in order to reduce the defect density, and the relationship between residue hydrogen concentration, fluence and step width is discussed. Finally, the combined effects show that the single-step process of surface texturing and step-by-step crystallization induced by excimer laser processing are promising for a-Si:H thin-film solar cell applications.

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“…Studies have demonstrated that processing of materials using ultrafast laser pulses is a feasible route for the fabrication nanostructures with diverse materials [13]. Synthesis of crystalline silicon nanostructures using femtosecond laser pulses at KHz pulse repetition rate under vacuum in a gaseous environment is reported [14][15][16][17]. Recently a competent approach for increasing the rate of production and size reduction of silicon nanoparticles using femtosecond double-pulse laser ablation of silicon in ethanol is proposed [18].…”

Section: Introductionmentioning

confidence: 99%

Composition of silicon fibrous nanostructures synthesized using ultrafast laser pulses under ambient conditions

Sivakumar

Venkatakrishnan

Tan

2015

MATEC Web of Conferences

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Abstract. In this study the composition of nanostructures generated owing to ablation of crystalline silicon using high repletion rate femtosecond laser under ambient condition is investigated. The web-like silicon fibrous nanostructures are formed in and around the laser irradiated area. Electron Microscopy investigation revealed that the nanostructures are made of nanoparticles of size about 40 nm. In addition Micro-Raman analysis shows that the nanofibrous structures comprises a mixture of amorphous and polycrystalline silicon. X-ray photoelectron spectroscopy analysis reveals the oxidized and un-oxidized elemental states of silicon in the nanostructures. Moreover web-like fibrous nanostructures are generated due to condensation of super saturated vapour and subsequent nucleus growth in the laser induced plasma plume.

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Silicon Surface Morphologies after Femtosecond Laser Irradiation

Cited by 165 publications

References 84 publications

Ultrafast laser direct hard-mask writing for high efficiency c-Si texture designs

Ultrafast laser direct hard-mask writing for high efficiency c-Si texture designs

Effect of hydrogen on surface texturing and crystallization of a-Si:H thin film irradiated by excimer laser

Composition of silicon fibrous nanostructures synthesized using ultrafast laser pulses under ambient conditions

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