engleski

Response of GaN to sequential ion irradiation

Behavior of materials in radiation harsh environment is an important issue because damage build-up within material in such environment can exhibit complex behavior. Therefore, as one of the candidate materials that can be used in radiation harsh environments, response of GaN to ion irradiation should be studied in detail. Dense electronic excitation in the wake of the swift heavy ion (mass > 20 amu, kinetic energy > 1 MeV/amu) can lead to nanoscale material damage along ion trajectory called ion track. Thermal spike scenario describes this process as transfer of the deposited swift heavy ion energy from the electronic subsystem into phonon subsystem via electron-phonon coupling. Permanent damage can be formed upon rapid quenching of the molten material if the density of deposited energy (usually expressed in terms of electronic energy loss of the swift heavy ion) is sufficient to induce melting. Irradiation with heavy ions in the keV energy range can also produce defects via different energy dissipation channel, namely nuclear energy loss. This process is known to introduce defects up to several hundred nanometers in depth. Depending on the applied ion fluence, damage build-up can lead even to complete amorphisation of the material within the ion range. Recently, synergistic effects of nuclear and electronic energy loss came into research focus. By means of molecular dynamics simulations, response of damaged wurzite GaN (defects introduced by keV ion irradiation) was studied when subjected to swift heavy ion irradiation, in order to investigate role of defects with respect to the ion track formation.

GaN ; swift heavy ion ; ion track ; MD simulation

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