PNNL

Abstract

Single crystal 6H-SiC has been irradiated 60 degrees off normal with 2 MeV Au2? ions at 300 K to fluences of 0.029, 0.058 and 0.12 ions/nm2, which produced relatively low damage levels. The disorder profiles as a function of ion fluence on both the Si and C sublattices have been determined simultaneously in situ using Rutherford backscattering and nuclear reaction analysis with 0.94 MeV D+ ions in channeling geometry along the , and axes. Along the axis at these low doses, similar levels of Si and C disorder are observed, and the damage accumulation is linear with dose. However, along and , the disorder accumulation is larger and increases sublinearly with dose. Furthermore, a higher level of C disorder than Si disorder is observed along the and axes, which is consistent with a smaller threshold displacement energy on the C sublattice in SiC. The mean lattice displacement, perpendicular to each corresponding axis, ranges from 0.014 to 0.037 nm for this range of ion fluences. A steady accumulation of small displacements due to lattice stress is observed along the axis, and a detectable reduction of the lattice stress perpendicular to the axis occurs at 0.12 Au2?/nm2. There is only a moderate recovery of disorder, produced at and below 0.058 Au2?/nm2, during thermal annealing at 570 K; more significant recovery is observed for 0.12 Au2?/nm2 along both the and axes.