Electronic excitations induced climb of dislocations in swift heavy ion irradiated AlN and Al_xGa_(1-x)N

摘要

Recent work has shown that electronic excitations play a role in the creation of optical point defects in AlN although the material had been considered during a long time as insensitive to electronic energy loss and radiolysis. We address here an indirect observation of the effect of electronic excitations on point defect in AlN. Unprecedented climb of screw dislocations under swift heavy irradiation in irradiated AlN is studied. This is a sign to point defect diffusion towards the dislocation, which allows the increase of the length of the dislocation line. It is demonstrated that the climb, thus the point defect creation and/or their mobility is mainly induced by electronic excitations. This happens above an electronic stopping power threshold much lower than the one for ion track formation in AlN. This climb of dislocation was also observed for the same irradiation conditions in AlxGa1-xN (x = 0.5; 0.7; 0.8).