Insight into electronic mechanisms of nanosecond-laser ablation of silicon

Abstract

To cite this version:Wladimir Marine, N.M. Bulgakova, Lionel Patrone, Igor Ozerov. Insight into electronic mechanisms of nanosecond-laser ablation of silicon. We present experimental and theoretical studies of nanosecond ArF excimer laser desorption and ablation of silicon with insight into material removal mechanisms. The experimental studies involve a comprehensive analysis of the laser-induced plume dynamics and measurements of the charge gained by the target during irradiation time. At low laser fluences, well below the melting threshold, high-energy ions with a narrow energy distribution are observed. When the fluence is increased, a thermal component of the plume is formed superimposing on the nonthermal ions, which are still abundant. The origin of these ions is discussed on the basis of two modeling approaches, thermal and electronic, and we analyze the dynamics of silicon target excitation, heating, melting, and ablation. An electronic model is developed that provides insight into the charge-carrier transport in the target. We demonstrate that, contrary to a commonly accepted opinion, a complete thermalization between the electron and lattice subsystems is not reached during the nanosecond-laser pulse action. Moreover, the charging effects can retard the melting process and have an effect on the overall target behavior and laser-induced plume dynamics.

Wavelength-dependent variations of the electron characteristics in laser-induced plasmas: A combined hydrodynamic and adiabatic expansion modelling and time-gated, optical emission imaging study

“…The line shape analysis does not require local thermodynamic equilibrium (LTE)-an assumption that will rarely be applicable to LIPs produced in vacuum. 15,16 Analyses of the plume accompanying PLA of Si in vacuum have been previously reported, 17 but only at a much shorter wavelength (193 nm) and lower fluences (F < 10 J cm −2 ). The present experimental data are compared with model outputs for the corresponding ablation in vacuum using a combination of numerical (during the laser pulse) and analytical (after the laser pulse) approaches.…”

Photoluminescence analysis of colloidal silicon nanoparticles in ethanol produced by double-pulse ns laser ablation

“…In DPLA process, the energy density of pre-pulse (~1 J cm -2 per shot) is higher than the melting threshold of silicon (~0.4 J/cm 2 ) [51]. Thus, the interaction of pre-pulse with the target surface can result in heating and melting of the silicon surface within the irradiated zone, and therefore the main delayed pulse may strongly interact with the melted silicon and get absorbed [52,53].…”

Double-pulse nanosecond laser ablation of silicon in water

“…Average size of the prepared Si NPs, and associated uncertainty, was estimated from SEM images illustrated in figure 6. [16][17][18][19][20][21][22]. For nanosecond PLA of semiconductors by IR-laser radiation, laser energy transfer to the target can result in excitation of free electrons (intra-band transitions) and vibrations within the materials [16].…”

“…For nanosecond PLA of semiconductors by IR-laser radiation, laser energy transfer to the target can result in excitation of free electrons (intra-band transitions) and vibrations within the materials [16]. This process has been mainly studied on the basis of thermal and photo-physical models [16][17][18][19][20][21][22]. In general, with low to medium laser intensities, the excitation energy is dissipated into heat so fast that the laser beam can simply be considered as a heat source which induces a temperature rise on the surface and within the bulk of the material [16].…”