Tóm tắt

Mechanical property changes of 4H–SiC implanted at room temperature with helium ions at fluences ranging from 7 · 1015 torn1 · 1017 cmu00022 and at an ion energy of 50 keV were investigated by using nano-indentation tests and subsequent atomic force microscopyrninvestigations. Degradation of the mechanical properties of the near-surface due to helium implantation was analysed and correlatedrnwith the microstructure evolution examined through transmission electron microscopy cross-section and X-ray diffraction experiments.rnUp to 1 · 1016 He+ cmu00022 no significant change in mechanical properties is seen whereas a normal strain profile of few percents isrngenerated all along the ion path. Nevertheless, the as-created implantation damage enhance the dislocation nucleation. At intermediaternfluences, when a buried amorphous layer is created, the hardness curve against penetration depth can be divided into three stages showing ‘constraining coating’ effects. When the entire part of the implanted crystal is amorphous a decrease of about 50% is measured forrnhardness value.