Transient thermal processes in heavy ion irradiation of crystalline inorganic insulators

Nanoporous SiO2/Si thin layers produced by ion track etching: Dependence on the ion energy and criterion for etchability

“…The i-TS model is the only model available to describe quantitatively the threshold of damage creation and the track size in insulators, taking into account the incident ion velocity. 8,20,32 It tries to establish a link between the initial energy deposition on the electrons and the resulting damage creation in the lattice by introducing the electron-phonon mean free path that characterizes the length of energy diffusion on the electrons prior to its transfer to the lattice. 33 In this model, it is assumed that the induced track size results from a cylinder zone which contains sufficient energy E m for melting ͑defined by the energy to reach the melting temperature plus the latent heat of fusion 20,32 ͒.…”

“…A͑r , t͒ is related to the kinetic energy of the projectiles thermalized in the electron system within about 10 −15 s. A͑r , t͒ is normalized to ensure that the integration in space and time is equal to the total energy loss S e . 34 The two differential equations are solved numerically as a function of space and time interval ͑dt͒, using the electronphonon coupling term g. 20,[34][35][36] The energy deposited on the electrons is followed assuming the known thermal conductivity. Via the specific heat, the difference in temperature between the electron and lattice subsystems ͓T e ͑r , t͒ − T a ͑r , t − dt͔͒ multiplied by ͑g ϫ dt͒ gives the part of the energy transferred to the atomic subsystem during dt.…”

“…This allowed us to conclude that the nuclear fraction of the deposited energy has a negligible influence on the formation of etchable tracks in SiO 2 , even when the nuclear stopping is higher than the electronic one. Furthermore, we applied the inelastic thermal-spike ͑i-TS͒ model 9,20 to rationalize the data on etched pore morphology and size distribution as a function of S e . The model can correctly ascribe the threshold stopping power for the appearance of an etchable track and for homogeneous etching, giving support to the idea that the melting of the a-SiO 2 structure is directly linked to the etchability of the ion tracks.…”

Femtosecond laser and swift-ion damage in lithium niobate: A comparative analysis

“…A number of proposals and strategies have been advanced to understand the damage effects of ion irradiation, namely, thermal spike models 15,25 followed by melting and/or ablation, exciton models, 38,39 and molecular dynamics calculations. 40,41 For femtosecond-laser pulse irradiation, a variety of models have also been invoked.…”

“…7,[10][11][12][13] In such electronic regime, individual ions generate amorphous ͑latent͒ tracks of only a few nanometers in diameter [14][15][16] when the electronic stopping power overcomes a certain threshold value, which depends on material and, at a lesser extent, on irradiation conditions. This technique opens new possibilities for nanostructuring of materials and may compete with femtosecond-laser pulse irradiation.…”