Structure and mechanical properties of He-implanted SiC

The changes in microstructure and mechanical properties of 4H-SiC implanted at room temperature with 50 keV helium ions have been studied. Up to 1 × 1016 cm−2, no significant change in mechanical properties is observed. Nevertheless, the as-created damage that induce a normal strain profile of few percents, enhance the dislocation nucleation. The compressive in-plane stress impedes the crack formation. At medium fluences, when a buried amorphous layer is created, the hardness curve against penetration depth can be divided into three stages showing “constraining coating” effects. Indents are surrounded by large hillocks resulting from the flowing of the amorphous state. When the entire part of the implanted crystal is amorphous a large decrease is measured for both the hardness and elastic modulus.