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Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 18, Iss. 18 — Aug. 30, 2010
  • pp: 19379–19385
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Femtosecond laser induced surface nanostructuring and simultaneous crystallization of amorphous thin silicon film

X. C. Wang, H. Y. Zheng, C. W. Tan, F. Wang, H. Y. Yu, and K. L. Pey  »View Author Affiliations


Optics Express, Vol. 18, Issue 18, pp. 19379-19385 (2010)
http://dx.doi.org/10.1364/OE.18.019379


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Abstract

Ultrafast pulsed laser irradiation is demonstrated to be able to produce surface nano-structuring and simultaneous crystallization of amorphous silicon thin film in one step laser processing. After fs laser irradiation on 80 nm-thick a-Si deposited on Corning 1737 glass substrate, the color change from light yellow to dark brown was observed on the sample surface. AFM images show that the surface nano-spike pattern was produced on amorphous-Si:H film by fs laser irradiation. Furthermore, micro-Raman results indicate that the a-Si has been crystallized into nanocrystalline Si. Also, the absorptance of the fs laser treated Si thin film was found to increase in the spectrum range of below bandgap compared to original untreated a-Si. The developed process has a potential application in fabrication of high efficiency Si thin film solar cells.

© 2010 OSA

1. Introduction

Hydrogenated amorphous silicon (a-Si:H) is one of the most widely used material for photovoltaics application due to its low fabrication cost compared to their crystalline counterpart because of its high deposition rate, low deposition temperature, which can enable the usage of inexpensive substrates such as glass, plastic and metal foils. However, the metastable structure of amorphous silicon films needs to be continuously improved to address the concerns on low carrier mobility, high reflectivity across the electromagnetic spectrum and light-induced degradation (Staebler-Wronski (S-W) effect) [1

1. D. L. Staebler and C. R. Wronski, “Reversible conductivity changes in discharge produced amorphous Si,” Appl. Phys. Lett. 31(4), 292–294 (1977). [CrossRef]

], for PV applications. In order to improve the efficiency and sensitivity of a-Si based devices, a post processing is usually needed. Crystallization of a-Si:H has been studied as one of the potential solutions to this problem [2

2. A. A. D. T. Adikaari and S. R. P. Silva, “Thickness dependence of properties of excimer laser crystallized nano-polycrystalline silicon,” J. Appl. Phys. 97(11), 114305 (2005). [CrossRef]

5

5. D. Song, D. Inns, A. Straub, M. L. Terry, P. Campbell, and A. G. Aberle, “Solid phase crystallized polycrystalline thin-films on glass from evaporated silicon for photovoltaic applications,” Thin Solid Films 513(1–2), 356–363 (2006). [CrossRef]

]. Excimer laser crystallization has been a preferred technique for crystallization of a-Si:H deposited on cheap substrates such as glass. Upon irradiation, melting and solidifying of the a-Si:H film occur during tens of nanoseconds, with the melt depth mainly determined by the laser energy density, often without affecting the underlying substrate. Recently, ultrafast laser-induced crystallization of amorphous silicon film has been investigated as a new approach for crystallization purpose [6

6. T. Y. Choi, D. J. Hwang, and C. P. Grigoropoulos, “Ultrafast laser-induced crystallization of amorphous silicon films,” Opt. Eng. 42(11), 3383–3388 (2003). [CrossRef]

8

8. B. K. Nayak and M. C. Gupta, “Femtosecond-laser-induced-crystallization and simultaneous formation of light traping microstructures in thin a-Si:H films,” Appl. Phys., A Mater. Sci. Process. 89(3), 663–666 (2007). [CrossRef]

]. Unlike excimer laser annealing process, ultrafast pulsed laser interaction with a-Si thin film material involves nonlinear photoenergy absorption and nonequilibrium thermodynamics that are expected to dominate the interaction [9

9. S. K. Sundaram and E. Mazur, “Inducing and probing non-thermal transitions in semiconductors using femtosecond laser pulses,” Nat. Mater. 1(4), 217–224 (2002). [CrossRef]

11

11. K. Sokolowski-Tinten, J. Bialkowski, and D. von der Linde, “Ultrafast laser-induced order-disorder transitions in semiconductors,” Phys. Rev. B Condens. Matter 51(20), 14186–14198 (1995). [CrossRef] [PubMed]

]. Such a nonlinear process provides precise and low-threshold fluence associated with femtosecond laser ablation [6

6. T. Y. Choi, D. J. Hwang, and C. P. Grigoropoulos, “Ultrafast laser-induced crystallization of amorphous silicon films,” Opt. Eng. 42(11), 3383–3388 (2003). [CrossRef]

,11

11. K. Sokolowski-Tinten, J. Bialkowski, and D. von der Linde, “Ultrafast laser-induced order-disorder transitions in semiconductors,” Phys. Rev. B Condens. Matter 51(20), 14186–14198 (1995). [CrossRef] [PubMed]

,12

12. X. Liu, D. Du, and G. Mourou, “Laser ablation and micromachining with ultrashort laser pulses,” IEEE J. Quantum Electron. 33(10), 1706–1716 (1997). [CrossRef]

]. In this paper, we demonstrated that infrared femtosecond laser is able to induce crystallization of amorphous silicon and simultaneous surface nanostructuring on a-Si:H surface in one step process. Upon fs laser treatment, the absorbance of the a-Si:H thin film is increased due to the crystallization and surface nanotexturing. The developed process has potential application for fabrication of high efficiency Si thin film solar cells, thin film transistor (TFT) for AMLCD application, and other novel optoelectronic devices.

2. Experimental

The amorphous silicon films of thickness of 80 nm were deposited onto Corning 1737 glass substrates, using a low temperature plasma enhanced chemical vapor deposition (PECVD) technique. The samples were treated with a femtosecond laser beam. The fs laser system used is based on a regenerative Ti:Sapphire amplifier using chirped pulse amplification technique (Clark-MXR, CPA 2001) which provides high-intensity fs laser pulses for the processes. The pulse duration of the output beam from amplifier is 150 fs with nominal wavelength at 775 nm. The repetition rate is 1000 Hz and the beam profile emitted from the regenerative amplifier is approximately Gaussian shape. The average output power can reach 800 mW at repetition rate of 1000 Hz. The sample was placed on a stationary stage and the laser beam was deflected by a Scanlab galvanometer scanner for scanning treatment of the sample surface. The focused beam spot size was measured to be around 30 μm of the diameter on the sample surface. In order to find optimum conditions, the laser scanning treatments were conducted at various laser fluencies from 1 mJ/cm2 to 50 mJ/cm2 and scanning speeds from 1 mm/s to 100 mm/s. The morphology of the laser treated samples was analyzed using optical microscope, scanning electron microscopy (SEM), and atom force microscope (AFM, Digital Instruments, Nanoscope III). Micro-Raman spectra are recorded at room temperature with Renishaw’s inVia Raman microscope in backscattering geometry using 514 nm line of argon ion laser. The transmittance and reflectance were measured with UV-VIS-NIR scanning spectrophotometer (UV3101PC).

3. Results and discussion

Figure 1
Fig. 1 Optical microscope image of fs laser treated a-Si:H thin film.
shows the optical microscope image of laser treated and untreated surfaces of a-Si:H film deposited on a Corning 1737 glass substrate where the laser fluence was 6.9 mJ/cm2 and scanning speed was 20 mm/s. It can be clearly seen that after laser irradiation the a-Si film was turned into dark brown from original shinny light yellow color, which indicates the surface property such as surface finish, and phase state might change after laser treatment.

Figure 2
Fig. 2 SEM images of (a) original a-Si:H thin film surface and (b) fs laser treated a-Si:H thin film surface.
shows the scanning electron microscope (SEM) images of original and laser treated Si surfaces. It is obvious from the image that surface nano-structures have been formed upon laser treatment. Further enlarged by AFM images as shown in Fig. 3
Fig. 3 AFM images of (a) original a-Si:H thin film surface and (b) fs laser treated a-Si:H thin film surface.
, it was observed that a regular nano-spike patterned texture was formed after fs laser irradiation. The distance between the nano-spikes is about 200 nm and the diameter of the formed nanobump is about 90 nm at full width at half maximum (FWHM) and its height is about 20 nm.

The produced nano-spike pattern is expected to be beneficial to reducing the light reflectance, so as to increase light trapping. Actually, femtosecond laser induced nano-spike patterned ‘black silicon’ has been achieved and extensively studied by Mazur’s group on crystalline bulk silicon substrate [13

13. T. H. Her, R. J. Finlay, C. Wu, S. Deliwala, and E. Mazur, “Microstructuring of silicon with femtosecond laser pulses,” Appl. Phys. Lett. 73(12), 1673–1675 (1998). [CrossRef]

,14

14. T. H. Her, R. J. Finlay, C. Wu, and E. Mazur, “Femtosecond laser-induced formation of spikes on silicon,” Appl. Phys., A Mater. Sci. Process. 70(4), 383–385 (2000). [CrossRef]

], where the crystalline Si substrate was processed in the presence of a sulfur containing gas such as SF6. The nano-spike patterned black silicon surface was demonstrated to be strongly light-absorbing and the surface of silicon, normally gray and shiny, turned deep black. Also, the surface textured black silicon has been realized with reactive ion etching (RIE) on mono-crystalline and multi-crystalline silicon wafers [15

15. H. Jansen, M. de Boer, R. Legtenberg, and M. Elwenspoek, “The black silicon method: a universal method for determining the parameter setting of a fluorine-based reactive ion etcher in deep silicon trench etching with profile control,” J. Micromech. Microeng. 5(2), 115–120 (1995). [CrossRef]

,16

16. J. S. Yoo, I. O. Parm, U. Gangopadhyay, K. Kim, S. K. Dhungel, D. Mangalaraj, and J. Yi, “Black silicon layer formation for application in solar cells,” Sol. Energy Mater. Sol. Cells 90(18-19), 3085–3093 (2006). [CrossRef]

]. The etched silicon surface showed a significant reduced reflectance in the visible region as well as in near-IR region.

To study the crystalline property of the laser treated area, micro-Raman analysis was conducted. Raman spectroscopy is a sensitive probe to local atomic arrangement and vibrations (phonons) in solids [17

17. A. K. Arora, M. Rajalakshmi, and T. R. Ravindran, “Phonon Confinement in Nanostructured Materials,” Encyclopedia of Nanoscience and Nanotechnology 8, 499–512, (2004).

] and this technique has been used to characterize nanostructures that provide information about the nature of crystalline structure or amorphous disorder structure.

Figure 4
Fig. 4 Raman spectra of original and laser treated a-Si:H thin film, the dashed lines are Gaussian profile fittings.
showed micro-Raman spectra for as-grown a-Si thin film and fs laser treated a-Si thin film, where the Gaussian line profiles fitting has been conducted to the Raman spectra of untreated and fs laser treated a-Si:H film as the dashed lines. As shown in Fig. 4, it can be seen that for as grown a-Si:H, the Raman spectrum consists mainly of two broad peaks, one peak centered at 465.55 cm−1 which is characteristic of amorphous silicon corresponding to the TO zone-edge phonon, and another broad peak centered at 332.20 cm−1 which is attributed to LO amorphous phonon mode [18

18. C. Smit, R. A. C. M. M. Van Swaaij, H. Donker, A. M. H. N. Petit, W. M. M. Kesels, and M. C. M. van de Sanden, “Determining the material structure of microcrystalline silicon from Raman spectra,” J. Appl. Phys. 94(5), 3582–3588 (2003). [CrossRef]

].

After fs laser treatment, interestingly, besides two broad-bands at 477.97 and 347.78 cm−1, the Raman spectra shows a sharp Raman peak centered at 511.7 cm−1, which is an evidence of a crystalline phase. However, the sharp peak is shifted by an amount of 8.3 cm−1 from the peak at 520 cm−1 that corresponds to bulk crystalline silicon. This shift might be attributed to phonon confinement [19

19. E. Fogarassy, H. Pattyn, M. Elliq, A. Slaoui, B. Prevot, R. Stuck, S. deUnamuno, and E. L. Mathe, “Pulsed-laser crystallization and doping for the fabrication of high-quality poly-Si TFTs,” Appl. Surf. Sci. 69(1–4), 231–241 (1993). [CrossRef]

], possibly due to the presence of nanocrystals embedded in a-Si:H environment. Stress-induced effects are also reported to cause this behavior. As a result, in Fig. 4, the two distinct peaks at 511.7 and 477.97 cm−1 for the fs laser treated a-Si:H thin film are believed to be corresponding to an mixed phase silicon consisting of an amorphous phase and crystalline phase. In mixed phase silicon, the momentum selection rule of the Raman process is more relaxed compared to crystalline silicon. With increasing momentum the TO photon energy lowers, leading to broadening of the Raman peak towards the lower energies [18

18. C. Smit, R. A. C. M. M. Van Swaaij, H. Donker, A. M. H. N. Petit, W. M. M. Kesels, and M. C. M. van de Sanden, “Determining the material structure of microcrystalline silicon from Raman spectra,” J. Appl. Phys. 94(5), 3582–3588 (2003). [CrossRef]

,20

20. A. T. Voutsas, M. K. Hatalis, J. Boyce, and A. Chiang, “Raman spectroscopy of amorphous and microcrystalline silicon films deposited by low-pressure chemical vapor deposition,” J. Appl. Phys. 78(12), 6999–7006 (1995). [CrossRef]

]. The crystalline volume fraction of the fs laser treated sample can be calculated from the integrated intensities of the Raman peaks with Gaussian fits for the amorphous peak (Ia) and the crystalline peak (Ic) as shown in Fig. 4. The calculation was done as proposed by Tsu et al. with crystalline volume fraction (Χc) given by Eq. (1), where γ is the ratio of the backscattering cross-section of amorphous and crystalline phases [21

21. R. Tsu, J. Gonzalez-Hernandez, S. S. Chao, S. C. Lee, and K. Tanaka, “Critical volume fraction of crystallinity for conductivity percolation in phosphorus-doped Si-F-H alloys,” Appl. Phys. Lett. 40(6), 534–535 (1982). [CrossRef]

],

Χc=IcIc+(γ)Ia
(1)

The selection of a value of γ is complex due to its dependency on absorption coefficient of amorphous and crystalline silicon [22

22. E. Bustarret, M. A. Hachicha, and M. Brunel, “Experimental-determination of the nanocrystalline volume fraction in silicon thin films from Raman-spectroscopy,” Appl. Phys. Lett. 52(20), 1675–1677 (1988). [CrossRef]

]. γ has been calculated to be between 0.8 and 0.9, the most widely used value being 0.8 for mixed phase silicon [20

20. A. T. Voutsas, M. K. Hatalis, J. Boyce, and A. Chiang, “Raman spectroscopy of amorphous and microcrystalline silicon films deposited by low-pressure chemical vapor deposition,” J. Appl. Phys. 78(12), 6999–7006 (1995). [CrossRef]

,22

22. E. Bustarret, M. A. Hachicha, and M. Brunel, “Experimental-determination of the nanocrystalline volume fraction in silicon thin films from Raman-spectroscopy,” Appl. Phys. Lett. 52(20), 1675–1677 (1988). [CrossRef]

]. Here, γ was taken to be 0.8. According to Eq. (1), based on the integrated intensities of crystalline part and amorphous part in Fig. 4, the crystalline volume fraction of fs laser treated a-Si:H thin film was determined to be approximately 34.7%.

In order to study the optical characteristics we measured the reflectance and transmittance of as-grown and laser treated a-Si thin film with an area of 20 x 20 mm2 using a spectrophotometer. The reflectance (R in %) and transmittance (T in %) were then used to obtain the absorbance (α in %) of the samples: α = 1-R-T. Figure 5
Fig. 5 Absorptance of original and laser treated a-Si:H thin film.
shows the absorbance of laser treated and original a-Si films. It is clear from Fig. 5 that there is a significant enhancement in the optical absorption below the a-Si:H band gap (1.7 eV) in the case of laser treated films.

It is suggested that the increase of below band edge absorption might be due to the textured surface resulting from laser treatment, by helping to trap the light due to multiple reflection. Furthermore, the increase in the absorption is most probably caused by the reduction in the reflection which could be due to the anti-reflective properties of the fs laser formed nano spikes which may have gradient index structure [23

23. Y. F. Huang, S. Chattopadhyay, Y. J. Jen, C. Y. Peng, T. A. Liu, Y. K. Hsu, C. L. Pan, H. C. Lo, C. H. Hsu, Y. H. Chang, C. S. Lee, K. H. Chen, and L. C. Chen, “Improved broadband and quasi-omnidirectional anti-reflection properties with biomimetic silicon nanostructures,” Nat. Nanotechnol. 2(12), 770–774 (2007). [CrossRef]

]. Also, structural defects induced during the laser surface texturing process may likely produce bands of defect and impurity states in the band gap and thus enhances the overall absorption further [8

8. B. K. Nayak and M. C. Gupta, “Femtosecond-laser-induced-crystallization and simultaneous formation of light traping microstructures in thin a-Si:H films,” Appl. Phys., A Mater. Sci. Process. 89(3), 663–666 (2007). [CrossRef]

].

4. Conclusions

In conclusion, one step fs laser processing to produce surface nano-structuring and simultaneous crystallization of amorphous silicon thin film was developed. Fs laser irradiation on 80 nm-thick a-Si deposited on Corning 1737 glass substrate led to a color change from light yellow to dark brown on the sample surface. The a-Si:H thin film was converted to nanocrystalline silicon and at the same time, nano-spike texturing was fabricated on the surface of amorphous-Si:H film. The crystalline volume fraction of fs laser treated a-Si:H thin film was determinted to be about 34.7%. The absorptance of the fs laser treated Si thin film was found to increase compared to original untreated a-Si. The developed process has potential applications for high efficiency Si thin film solar cells, thin film transistors, large area sensors, and other novel optoelectronic devices.

Acknowledgements

The project was funded by a grant from the Agency for Science, Technology and Research of Singapore (A-STAR).

References and links

1.

D. L. Staebler and C. R. Wronski, “Reversible conductivity changes in discharge produced amorphous Si,” Appl. Phys. Lett. 31(4), 292–294 (1977). [CrossRef]

2.

A. A. D. T. Adikaari and S. R. P. Silva, “Thickness dependence of properties of excimer laser crystallized nano-polycrystalline silicon,” J. Appl. Phys. 97(11), 114305 (2005). [CrossRef]

3.

F. Falk and G. Andra, “Laser crystallization - a way to produce crystalline silicon films on glass or on polymer substrates,” J. Cryst. Growth 287(2), 397–401 (2006). [CrossRef]

4.

L. Carnel, I. Gordon, D. Van Gestel, K. Van Nieuwenhuysen, G. Agostinelli, G. Beaucarne, and J. Poortmans, “Thin-film polycrystalline silicon solar cells on ceramic substrates with a V-oc above 500 mV,” Thin Solid Films 511–512, 21–25 (2006). [CrossRef]

5.

D. Song, D. Inns, A. Straub, M. L. Terry, P. Campbell, and A. G. Aberle, “Solid phase crystallized polycrystalline thin-films on glass from evaporated silicon for photovoltaic applications,” Thin Solid Films 513(1–2), 356–363 (2006). [CrossRef]

6.

T. Y. Choi, D. J. Hwang, and C. P. Grigoropoulos, “Ultrafast laser-induced crystallization of amorphous silicon films,” Opt. Eng. 42(11), 3383–3388 (2003). [CrossRef]

7.

J. M. Shieh, Z. H. Chen, B. T. Dai, Y. C. Wang, A. Zaitsev, and C. L. Pan, “Near-infrared femtosecond laser-induced crystallization of amorphous silicon,” Appl. Phys. Lett. 85(7), 1232–1234 (2004). [CrossRef]

8.

B. K. Nayak and M. C. Gupta, “Femtosecond-laser-induced-crystallization and simultaneous formation of light traping microstructures in thin a-Si:H films,” Appl. Phys., A Mater. Sci. Process. 89(3), 663–666 (2007). [CrossRef]

9.

S. K. Sundaram and E. Mazur, “Inducing and probing non-thermal transitions in semiconductors using femtosecond laser pulses,” Nat. Mater. 1(4), 217–224 (2002). [CrossRef]

10.

A. Rousse, C. Rischel, S. Fourmaux, I. Uschmann, S. Sebban, G. Grillon, Ph. Balcou, E. Förster, J. P. Geindre, P. Audebert, J. C. Gauthier, and D. Hulin, “Non-thermal melting in semiconductors measured at femtosecond resolution,” Nature 410(6824), 65–68 (2001). [CrossRef] [PubMed]

11.

K. Sokolowski-Tinten, J. Bialkowski, and D. von der Linde, “Ultrafast laser-induced order-disorder transitions in semiconductors,” Phys. Rev. B Condens. Matter 51(20), 14186–14198 (1995). [CrossRef] [PubMed]

12.

X. Liu, D. Du, and G. Mourou, “Laser ablation and micromachining with ultrashort laser pulses,” IEEE J. Quantum Electron. 33(10), 1706–1716 (1997). [CrossRef]

13.

T. H. Her, R. J. Finlay, C. Wu, S. Deliwala, and E. Mazur, “Microstructuring of silicon with femtosecond laser pulses,” Appl. Phys. Lett. 73(12), 1673–1675 (1998). [CrossRef]

14.

T. H. Her, R. J. Finlay, C. Wu, and E. Mazur, “Femtosecond laser-induced formation of spikes on silicon,” Appl. Phys., A Mater. Sci. Process. 70(4), 383–385 (2000). [CrossRef]

15.

H. Jansen, M. de Boer, R. Legtenberg, and M. Elwenspoek, “The black silicon method: a universal method for determining the parameter setting of a fluorine-based reactive ion etcher in deep silicon trench etching with profile control,” J. Micromech. Microeng. 5(2), 115–120 (1995). [CrossRef]

16.

J. S. Yoo, I. O. Parm, U. Gangopadhyay, K. Kim, S. K. Dhungel, D. Mangalaraj, and J. Yi, “Black silicon layer formation for application in solar cells,” Sol. Energy Mater. Sol. Cells 90(18-19), 3085–3093 (2006). [CrossRef]

17.

A. K. Arora, M. Rajalakshmi, and T. R. Ravindran, “Phonon Confinement in Nanostructured Materials,” Encyclopedia of Nanoscience and Nanotechnology 8, 499–512, (2004).

18.

C. Smit, R. A. C. M. M. Van Swaaij, H. Donker, A. M. H. N. Petit, W. M. M. Kesels, and M. C. M. van de Sanden, “Determining the material structure of microcrystalline silicon from Raman spectra,” J. Appl. Phys. 94(5), 3582–3588 (2003). [CrossRef]

19.

E. Fogarassy, H. Pattyn, M. Elliq, A. Slaoui, B. Prevot, R. Stuck, S. deUnamuno, and E. L. Mathe, “Pulsed-laser crystallization and doping for the fabrication of high-quality poly-Si TFTs,” Appl. Surf. Sci. 69(1–4), 231–241 (1993). [CrossRef]

20.

A. T. Voutsas, M. K. Hatalis, J. Boyce, and A. Chiang, “Raman spectroscopy of amorphous and microcrystalline silicon films deposited by low-pressure chemical vapor deposition,” J. Appl. Phys. 78(12), 6999–7006 (1995). [CrossRef]

21.

R. Tsu, J. Gonzalez-Hernandez, S. S. Chao, S. C. Lee, and K. Tanaka, “Critical volume fraction of crystallinity for conductivity percolation in phosphorus-doped Si-F-H alloys,” Appl. Phys. Lett. 40(6), 534–535 (1982). [CrossRef]

22.

E. Bustarret, M. A. Hachicha, and M. Brunel, “Experimental-determination of the nanocrystalline volume fraction in silicon thin films from Raman-spectroscopy,” Appl. Phys. Lett. 52(20), 1675–1677 (1988). [CrossRef]

23.

Y. F. Huang, S. Chattopadhyay, Y. J. Jen, C. Y. Peng, T. A. Liu, Y. K. Hsu, C. L. Pan, H. C. Lo, C. H. Hsu, Y. H. Chang, C. S. Lee, K. H. Chen, and L. C. Chen, “Improved broadband and quasi-omnidirectional anti-reflection properties with biomimetic silicon nanostructures,” Nat. Nanotechnol. 2(12), 770–774 (2007). [CrossRef]

24.

C. V. Shank, R. Yen, and C. Hirlimann, “Time-Resolved Reflectivity Measurements of Femtosecond-Optical-Pulse-Induced Phase Transitions in Silicon,” Phys. Rev. Lett. 50(6), 454–457 (1983). [CrossRef]

25.

M. C. Downer, R. L. Fork, and C. V. Shank, “Femtosecond imaging of melting and evaporation at a photoexcited silicon surface,” J. Opt. Soc. Am. B 2(4), 595–599 (1985). [CrossRef]

26.

K. Sokolowski-Tinten, J. Solis, J. Bialkowski, J. Siegel, C. N. Afonso, and D. Von der Linde, “Dynamics of Ultrafast Phase Changes in Amorphous GeSb Films,” Phys. Rev. Lett. 81(17), 3679–3682 (1998). [CrossRef]

27.

J. Solis, C. N. Afonso, S. C. W. Hyde, N. P. Barry, and P. M. W. French, “Existence of electronic excitation enhanced crystallization in GeSb amorphous thin films upon ultrashort laser pulse irradiation,” Phys. Rev. Lett. 76(14), 2519–2522 (1996). [CrossRef] [PubMed]

OCIS Codes
(140.3390) Lasers and laser optics : Laser materials processing
(160.6000) Materials : Semiconductor materials
(310.6860) Thin films : Thin films, optical properties

ToC Category:
Laser Microfabrication

History
Original Manuscript: June 3, 2010
Revised Manuscript: July 28, 2010
Manuscript Accepted: August 24, 2010
Published: August 27, 2010

Citation
X. C. Wang, H. Y. Zheng, C. W. Tan, F. Wang, H. Y. Yu, and K. L. Pey, "Femtosecond laser induced surface nanostructuring and simultaneous crystallization of amorphous thin silicon film," Opt. Express 18, 19379-19385 (2010)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-18-18-19379


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References

  1. D. L. Staebler and C. R. Wronski, “Reversible conductivity changes in discharge produced amorphous Si,” Appl. Phys. Lett. 31(4), 292–294 (1977). [CrossRef]
  2. A. A. D. T. Adikaari and S. R. P. Silva, “Thickness dependence of properties of excimer laser crystallized nano-polycrystalline silicon,” J. Appl. Phys. 97(11), 114305 (2005). [CrossRef]
  3. F. Falk and G. Andra, “Laser crystallization - a way to produce crystalline silicon films on glass or on polymer substrates,” J. Cryst. Growth 287(2), 397–401 (2006). [CrossRef]
  4. L. Carnel, I. Gordon, D. Van Gestel, K. Van Nieuwenhuysen, G. Agostinelli, G. Beaucarne, and J. Poortmans, “Thin-film polycrystalline silicon solar cells on ceramic substrates with a V-oc above 500 mV,” Thin Solid Films 511–512, 21–25 (2006). [CrossRef]
  5. D. Song, D. Inns, A. Straub, M. L. Terry, P. Campbell, and A. G. Aberle, “Solid phase crystallized polycrystalline thin-films on glass from evaporated silicon for photovoltaic applications,” Thin Solid Films 513(1–2), 356–363 (2006). [CrossRef]
  6. T. Y. Choi, D. J. Hwang, and C. P. Grigoropoulos, “Ultrafast laser-induced crystallization of amorphous silicon films,” Opt. Eng. 42(11), 3383–3388 (2003). [CrossRef]
  7. J. M. Shieh, Z. H. Chen, B. T. Dai, Y. C. Wang, A. Zaitsev, and C. L. Pan, “Near-infrared femtosecond laser-induced crystallization of amorphous silicon,” Appl. Phys. Lett. 85(7), 1232–1234 (2004). [CrossRef]
  8. B. K. Nayak and M. C. Gupta, “Femtosecond-laser-induced-crystallization and simultaneous formation of light traping microstructures in thin a-Si:H films,” Appl. Phys., A Mater. Sci. Process. 89(3), 663–666 (2007). [CrossRef]
  9. S. K. Sundaram and E. Mazur, “Inducing and probing non-thermal transitions in semiconductors using femtosecond laser pulses,” Nat. Mater. 1(4), 217–224 (2002). [CrossRef]
  10. A. Rousse, C. Rischel, S. Fourmaux, I. Uschmann, S. Sebban, G. Grillon, Ph. Balcou, E. Förster, J. P. Geindre, P. Audebert, J. C. Gauthier, and D. Hulin, “Non-thermal melting in semiconductors measured at femtosecond resolution,” Nature 410(6824), 65–68 (2001). [CrossRef] [PubMed]
  11. K. Sokolowski-Tinten, J. Bialkowski, and D. von der Linde, “Ultrafast laser-induced order-disorder transitions in semiconductors,” Phys. Rev. B Condens. Matter 51(20), 14186–14198 (1995). [CrossRef] [PubMed]
  12. X. Liu, D. Du, and G. Mourou, “Laser ablation and micromachining with ultrashort laser pulses,” IEEE J. Quantum Electron. 33(10), 1706–1716 (1997). [CrossRef]
  13. T. H. Her, R. J. Finlay, C. Wu, S. Deliwala, and E. Mazur, “Microstructuring of silicon with femtosecond laser pulses,” Appl. Phys. Lett. 73(12), 1673–1675 (1998). [CrossRef]
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