Bulk nucleation and amorphous phase formation in highly undercooled molten silicon

Wood, R. F.; Lowndes, D. H.; Narayan, J.

doi:10.1063/1.94912

Cited by 70 publications

(21 citation statements)

References 13 publications

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“…Our calculated values for 5 and 10 Å for critical size of diamond crystallite lead to A values of 10 25 and 10 24 cm −3 s −1 , respectively, which are consistent with our earlier results on homogeneous nucleation in super undercooled amorphous silicon 20 and theoretical estimates in carbon. 22 At the formation temperature, T r , the free energy of metastable diamond, highly undercooled carbon liquid, and amorphous diamond like carbon become equal.…”

Section: -21supporting

confidence: 80%

“…[18][19][20] Fig. 6(a) illustrates this super undercooling phenomenon in amorphous silicon, which had 500 nm thick amorphous silicon layer after (100) silicon was implanted with 200 keV self-ions to a dose 1.5 × 10 16 cm −2 .…”

Section: Gementioning

confidence: 99%

“…[18][19][20] The detailed modeling showed the nucleation of nanocrystallite (10 nm size) silicon from super undercooled melt and the time-resolved reflectivity measurements showed the importance of laser and substrate parameters, particularly the thermal conductivity of residual underlying amorphous layers, in achieving the undercooled state of silicon. 20,21 These results of undercooling in silicon emphasize the importance of low thermal conductivity substrates of sapphire and glass in the case of our diamond experiment. The formation of nanocrystalline region was found to be not a function of dopants, indicating the importance of homogeneous nucleation.…”

Section: Gementioning

confidence: 99%

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Research Update: Direct conversion of amorphous carbon into diamond at ambient pressures and temperatures in air

Narayan

Bhaumik

2015

APL Materials

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We report on fundamental discovery of conversion of amorphous carbon into diamond by irradiating amorphous carbon films with nanosecond lasers at room-temperature in air at atmospheric pressure. We can create diamond in the form of nanodiamond (size range <100 nm) and microdiamond (>100 nm). Nanosecond laser pulses are used to melt amorphous diamondlike carbon and create a highly undercooled state, from which various forms of diamond can be formed upon cooling. The quenching from the super undercooled state results in nucleation of nanodiamond. It is found that microdiamonds grow out of highly undercooled state of carbon, with nanodiamond acting as seed crystals.

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Section: -21supporting

confidence: 80%

Section: Gementioning

confidence: 99%

Section: Gementioning

confidence: 99%

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Research Update: Direct conversion of amorphous carbon into diamond at ambient pressures and temperatures in air

Narayan

Bhaumik

2015

APL Materials

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“…This can have the effect that a buried melt front is driven into the amorphous material leaving polycrystalline material behind. 8 In contrast to interfacial solidification, bulk solidification 1,2,9 is characterized by the formation of solid nuclei within a melt which is at homogeneous temperature.…”

Section: Introductionmentioning

confidence: 99%

Slow interfacial reamorphization of Ge films melted by ps laser pulses

Siegel¹,

Solı́s²,

Afonso³

1998

Journal of Applied Physics

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A first principles study of the lattice stability of diamond-structure semiconductors under intense laser irradiation J. Appl. Phys. 113, 023301 (2013) High-order sideband generation in bulk GaAs Appl. Phys. Lett. 102, 012104 (2013) Defect mediated reversible ferromagnetism in Co and Mn doped zinc oxide epitaxial films J. Appl. Phys. 112, 113917 (2012) Time-domain sampling of x-ray pulses using an ultrafast sample response Appl. Phys. Lett. 101, 243106 (2012) The effects of vacuum ultraviolet radiation on low-k dielectric films App. Phys. Rev. 2012Rev. , 12 (2012 Additional information on J. Appl. Phys. Melting and rapid solidification is induced in 50-nm-thick amorphous Ge films on glass substrates by single laser pulses at 583 nm with a duration of 10 ps. The solidification process is followed by means of reflectivity measurements with ns time resolution both at the air/film ͑front͒ and the substrate/film ͑back͒ interfaces. Due to interference effects between the light reflected at the filmsubstrate and film-liquid interfaces, the back side reflectivity measurements turn out to be very sensitive to the melt depth induced by the laser pulse and their comparison to optical simulations enables the determination of the solidification dynamics. For low fluences, only a thin layer of the film is melted and solidification occurs interfacially leading to reamorphization of the molten material. The results provide a critical interface velocity for amorphization of ϳ4 m/s, much slower than the one that has widely been reported for elementary semiconductors. For high fluences, the molten layer depth approaches the film thickness and the results are consistent with a bulk solidification process. In this case, recalescence effects upon solid phase nucleation become important and lead to the formation of crystallites distributed throughout the whole resolidified volume.

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“…By controlling the underlying growth template, it is also possible to create large-area single-crystal c-BN films. [21][22][23][24] Undercooling during high-power nanosecond pulsed laser irradiation in bulk materials of h-BN and carbon (HOPG, highly oriented pyrolytic graphite) is much smaller due to their high thermal conductivity. This has been confirmed by in situ synchrotron measurements in Si and Ge.…”

Section: Boron Nitride (Bn) Exists In Four Polymorphs Namely Hexagomentioning

confidence: 99%

Research Update: Direct conversion of h-BN into pure c-BN at ambient temperatures and pressures in air

Narayan

Bhaumik

2016

APL Materials

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We report a direct conversion of hexagonal boron nitride (h-BN) into pure cubic boron nitride (c-BN) by nanosecond laser melting at ambient temperatures and atmospheric pressure in air. According to the phase diagram, the transformation from h-BN into c-BN can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa. Using nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800 K and atmospheric pressure. The rapid quenching from super undercooled state leads to formation of super undercooled BN (Q-BN). The c-BN phase is nucleated from Q-BN depending upon the time allowed for nucleation and growth.

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Bulk nucleation and amorphous phase formation in highly undercooled molten silicon

Cited by 70 publications

References 13 publications

Research Update: Direct conversion of amorphous carbon into diamond at ambient pressures and temperatures in air

Research Update: Direct conversion of amorphous carbon into diamond at ambient pressures and temperatures in air

Slow interfacial reamorphization of Ge films melted by ps laser pulses

Research Update: Direct conversion of h-BN into pure c-BN at ambient temperatures and pressures in air

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