Theory for the instability of the diamond structure of Si, Ge, and C induced by a dense electron-hole plasma

Stampfli, P.; Bennemann, K. H.

doi:10.1103/physrevb.42.7163

Cited by 220 publications

(168 citation statements)

References 15 publications

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“…16 Concerning the reflectivity increase, it has been shown in previous publications 2,4 that nonthermal melting ͑NTM͒ can take place in InP for fluences already exceeding 1.4 ϫ⌽ abl ͑corresponding to an estimated carrier density of ϳ3 ϫ 10 22 cm −3 ͒, i.e., the generation of an electron-hole plasma with high carrier densities leading to a destabilization of the lattice structure within hundreds of femtoseconds. 17 Given the peak fluences used in Fig. 1 ͓͑a͒ 1.5ϫ⌽ abl ,..., ͑c͒ 8.5ϫ⌽ abl ͔, NTM is expected to occur in the center of the irradiated spots even if, given the time-resolution of 500 fs of our fs-TRM setup, we are not able to distinguish here between a reflectivity increase due to laser-generated carriers or due to nonthermal melting.…”

Section: Resultsmentioning

confidence: 96%

Time- and space-resolved dynamics of ablation and optical breakdown induced by femtosecond laser pulses in indium phosphide

Bachelier

Siegel

Solı́s

et al. 2008

Journal of Applied Physics

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Pulsed laser operated high rate charging of Fe-doped LiNbO3 crystal for electron emission J. Appl. Phys. 112, 073107 (2012) Formation of nanostructured TiO2 by femtosecond laser irradiation of titanium in O2 J. Appl. Phys. 112, 063108 (2012) Finite element calculations of the time dependent thermal fluxes in the laser-heated diamond anvil cell J. Appl. Phys. 111, 112617 (2012) Additional information on J. Appl. Phys. Femtosecond time-resolved microscopy has been used to analyze the structural transformation dynamics ͑melting, ablation, and solidification phenomena͒ induced by single intense 130 fs laser pulses in single-crystalline ͑100͒-indium phosphide wafers in air on a time scale from ϳ100 fs up to 8 ns. In the ablative regime close to the ablation threshold, transient surface reflectivity patterns are observed by fs microscopy on a ps to ns time scale as a consequence of the complex spatial density structure of the ablating material ͑dynamic Newton fringes͒. At higher fluences, exceeding six times the ablation threshold, optical breakdown causes another, more violent ablation regime, which reduces the energy deposition depth along with the time of significant material removal. As a consequence, ablation lasts longer in a ring-shaped region around the region of optical breakdown. This leads to the formation of a crater profile with a central protrusion. In the melting regime below the ablation threshold, the melting dynamics of indium phosphide has been quantified and subsequent superficial amorphization has been observed upon solidification on the ns time scale leading to amorphous layer thicknesses of the order of a few tens of nanometers.

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Section: Resultsmentioning

confidence: 96%

Time- and space-resolved dynamics of ablation and optical breakdown induced by femtosecond laser pulses in indium phosphide

Bachelier

Siegel

Solı́s

et al. 2008

Journal of Applied Physics

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“…This is due to the strong electronic excitation resulting in the formation of an electron-hole plasma, which can destabilize the lattice structure on a subpicosecond time scale when a critical electron density between 10 21 and 10 22 cm −3 in the conduction band is exceeded. 21 This ultrafast phase transition is usually referred to as nonthermal melting and has already been reported in germanium 11,12 and also in other semiconductors. 17,[22][23][24] Already after 1 ps, the reflectivity of the entire irradiated region has increased to almost the same reflectivity value as for the center of the image for 400 fs delay time, giving rise to the appearance of a bright elliptical area with a sharp defined edge ͓Fig.…”

Section: Fs-trmmentioning

confidence: 99%

Time- and space-resolved dynamics of melting, ablation, and solidification phenomena induced by femtosecond laser pulses in germanium

2006

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Femtosecond time-resolved microscopy has been used to analyze the structural transformation dynamics ͑melting, ablation, and solidification phenomena͒ induced by intense 130 fs laser pulses in single-crystalline ͑100͒-germanium wafers on a time scale from ϳ100 fs up to 10 ns. Complementary information on longer time scales ͑350 ps-1.4 s͒ has been obtained by means of simultaneous streak camera and photodiode measurements of the sample surface reflectivity. In the ablative regime, transient surface reflectivity patterns are observed by fs microscopy on a ps to ns time scale as a consequence of the complex spatial density structure of the ablating material. Complementing point-probing streak camera measurements allow one to characterize the temporal evolution in real time up to 40 ns after the fs-laser pulse excitation. Fs microscopy reveals additional reflectivity patterns for fluences below the ablation threshold of the germanium. It is shown that these patterns are originating from the selective removal of the native oxide layer at the wafer surface within a certain fluence range. After solidification, and in contrast to other semiconductors, surface amorphization has not been observed in ͑100͒-germanium upon femtosecond laser pulse irradiation in the studied fluence range.

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“…A Fermi-Dirac distribution of each carrier type is assumed but the chemical potential for electrons µ e − and for holes µ h + are not equal. (Previous theoretical investigations [8,9,10, 11] of short-time phonon dynamics in systems subjected to electronic excitation by ultrashort laser pulses have assumed, for technical reasons, that the chemical potential for electrons µ e − and for holes µ h + are equal; this is physically equivalent to assuming that the electron-hole recombination time is much shorter than the phonon period. )…”

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confidence: 99%

Calculations of theA1Phonon Frequency in Photoexcited Tellurium

Tangney

Fahy

1999

Phys. Rev. Lett.

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Calculations of the A 1 phonon frequency in photoexcited tellurium are presented. The phonon frequency as a function of photoexcited carrier density and phonon amplitude is determined. Recent pump probe experiments are interpreted in the light of these calculatons. It is proposed that, in conjunction with measurements of the phonon period in ultra-fast pump-probe reflectivity experiments, the calculated frequency shifts can be used to infer the evolution of the density of photoexcited carriers on a sub-picosecond time-scale.

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Theory for the instability of the diamond structure of Si, Ge, and C induced by a dense electron-hole plasma

Cited by 220 publications

References 15 publications

Time- and space-resolved dynamics of ablation and optical breakdown induced by femtosecond laser pulses in indium phosphide

Time- and space-resolved dynamics of ablation and optical breakdown induced by femtosecond laser pulses in indium phosphide

Time- and space-resolved dynamics of melting, ablation, and solidification phenomena induced by femtosecond laser pulses in germanium

Calculations of theA1Phonon Frequency in Photoexcited Tellurium

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