A novel method for simulating laser-solid interactions in semiconductors and layered structures

Singh, Rajiv K.; Narayan, J.

doi:10.1016/0921-5107(89)90014-7

Cited by 125 publications

(47 citation statements)

References 12 publications

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“…In the case of amorphous Ge and Si, highly under cooled states have been found to occur at 241 K and 336 K below their respective melting points. [6][7][8][9][10] Under the super undercooled state of silicon, bulk nucleation of nanocrystalline silicon was directly observed, where the nanocrystallites provided seed for macrograined polycrystalline silicon, as shown in TEM micrograph of Fig. 6.…”

Section: Gementioning

confidence: 99%

“…In the case of amorphous Ge and Si, highly undercooled states have been found to occur at 241 K and 336 K below their respective melting points. 6,7 By scaling with the melting point of carbon, we estimate the undercooling in carbon to be as high as 1000 K. This undercooling can shift amorphous carbon/diamond/liquid carbon triple point to 4000 K or lower at ambient pressures. The interface temperature was estimated to be 4000 K by laser-solid interactions calculations, Simulation of Laser Interaction with Materials (SLIM) model developed by Singh and Narayan.…”

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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: Gementioning

confidence: 99%

mentioning

confidence: 99%

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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“…These ablated species form a plasma plume containing mixture of atoms, molecules, electrons, and ions (Chrisey & Hubler, 1994;Doggett & Lunney, 2009;Lenk et al, 1996;Merlino, 2007;Singh & Narayan, 1990;Zheng et al, 1989;Wood & Giles, 1981;Caridi et al, 2008). The plasma plume expands with supersonic velocity (Singh & Narayan, 1989) and its parameters such as plasma temperature, ion density, electron density, electron temperature vary with laser parameters such as frequency, energy irradiance as well as on the background pressure (Inam et al, 1987;Neifeld et al, 1988). The laser produced plasma is highly transient in nature and its parameters vary in both space and time.…”

Section: Introductionmentioning

confidence: 98%

Plasma plume behavior of laser ablated cerium oxide: Effect of oxygen partial pressure

et al. 2014

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This paper describes the spatial and temporal investigation of laser ablated plasma plume of cerium oxide target using Langmuir probe. Cerium oxide target was ablated using a KrF (λ~248 nm) gas laser. Experimental studies confirmed that oxygen partial pressure of 2 × 10 −2 mbar is sufficient enough to get good quality films of cerium oxide. At this pressure, plume was diagnosed for their spatial and temporal behavior. Spatial distribution was investigated at a distance of 15 mm, 30 mm, and up to a maximum distance of 45 mm from the target, whereas temporal behavior has been recorded in the range of 0 to 50 μS with an interval of 0.5 μS. The average electron densities are found to be maximum at 30 mm from the target position and the plasma current of the laser ablated ceria is found to be maximum at 22 μS.

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“…At low laser irradiance, even though the one dimensional heat flow equation 3,4 has been used to obtain satisfactory estimates of the liquid-solid position compared to experimental results 5,6 , it doesn't include the vapor plume gas dynamics necessary to calculate the vapor phase front propagation, which is more relevant to the material removal rate from the surface by the laser pulses. Another possible approach is to use the Hertz-Knudsen equation in characterizing the vaporization flux 7 , yet reasonable correspondences between theoretical estimations and experimental data for the silicon removal speed at the low irradiance regime would require the magnitudes of the saturated vapor pressure to be at least one order larger than the critical pressure, which is hard to explain with reliable physics.…”

Section: Introductionmentioning

confidence: 98%

Nanosecond laser silicon micromachining

et al. 2004

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We present theoretical calculations and experimental measurements of silicon micromachining rates, efficiency of laser pulse utilization, and morphology changes under UV nanosecond pulses with intensities ranging from 0.5 GW/cm 2 to 150 GW/cm 2 . Three distinct irradiance regimes are identified based on laser intensity. At low intensity, proper gas dynamics and ablation vapor plume kinetics are taken into account in our theoretical modeling. At medium high intensity, we incorporate the proper plasma dynamics, and predict the effects of the laser generated vapor plasma and the electron hole plasma on the laser-matter interaction. At even higher intensity, we attribute the observed increased ablation rate to energy re-radiation from the laser heated hot plasma, the strong shock wave, and the accompanied strong shock wave heating effects. Experimentally measured data in these regimes agree well with our calculations, without changing parameters in the calculations used for the three regimes. Our results can be applied toward quantitatively characterize the behavior of ablation results under different laser parameters to achieve optimal results for micromachining of slots and vias on silicon wafers.

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A novel method for simulating laser-solid interactions in semiconductors and layered structures

Cited by 125 publications

References 12 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

Plasma plume behavior of laser ablated cerium oxide: Effect of oxygen partial pressure

Nanosecond laser silicon micromachining

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