The Temperature and Dose Dependency of Helium Reemission Ratio from Helium-ion-implanted Aluminium Samples

It has been observed that blisters and flakes appear on a metal surface implanted He ions above a specific ion dose called the critical dose. At the appearance of the blister and flake, He gas responsible for them is released. There are many reports on the gas reemission with these deformations but there are few reports about it below the critical dose. In this report, temperature and dose dependencies of He reemission from He-ion-implanted Al samples have been studied. After He ions of 20 keV are implanted in Al samples, the samples are heated in vacuum at 400, 450, 475, and 500℃ with holding time of 0.5, 1, and 2 hours. The numbers of He atoms remaining in the sample are measured by a He atom measurement system. The reemission ratios of the samples prepared at the given temperature and holding time have been obtained from comparison of the numbers of He ions implanted in the samples with the numbers of He atoms measured by the He atom measurement system. The reemission ratio rises with increasing temperature and holding time, and achieved at ～90% with 500℃ and 2 hours holding time. On dose dependency of the reemission ratio, it is constant up to 7×10^<14> He atoms and it increases rapidly above it