engleski

Lowering the threshold for ion track formation in GaN, MgO, MgAl2O4 and Al2O3

In radiation hard materials there is a rather high threshold in incoming ion energy below which ion track formation does not occur. However, this threshold can be significantly reduced by low energy pre-irradiation. As an example, previous studies on GaN found the threshold to be at about 20 keV/nm electronic stopping power for ion incidence close to normal to surface. It has been lowered down to 8 keV/nm after pre-irradiation by 2 MeV Au ions. This has been confirmed by RBS/c and AFM measurements where change in surface roughness has been found. Grazing incidence swift heavy ion irradiation effectively increases volume density of the absorbed energy leading to higher concentration of the formed defects. It also results in lowering of the ion track formation threshold. This has been studied in MgO, Al2O3 and MgAl2O4. Earlier results proved these materials to be radiation hard, and the threshold for the track formation is found to be in 10-15 keV/nm range for nearly normal irradiation. Switching to grazing incidence reduces the threshold down to 8 keV/nm. Here, the tracks are clearly visible on surface by AFM.

ion track ; swift heavy ion

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