Anisotropic defect distribution in He+-irradiated 4H-SiC: Effect of stress on defect distribution

Irradiation-induced anisotropic swelling in hexagonal α-SiC is known to degrade the mechanical properties of SiC; however, associated physical mechanism and microstructural process remain insufficiently understood. In this study, an condition where surface normal direction was allowed freely expand with constraint lateral introduced 4H-SiC using selected-area He+ irradiation, internal defect distribution investigated transmission electron microscopy (TEM) advanced scanning TEM. The compared that non-selected-area He+-irradiated electron-irradiated TEM-foil 4H-SiC. An observed He+-ion-irradiated 4H-SiC, interstitial defects preferentially redistributed ([0004]) negative volume (such as vacancies and/or carbon antisite defects) dominantly located directions ([112¯0] [101¯0]). This anisotropy substantially lower samples. stress three samples also measured analyzed. compressive (([101¯0] [112¯0])), little ([0004]); at beginning ion irradiation. likely inhibits formation directions, enhancing SiC.