Mechanical Properties and Defect Evolution of Kr-Implanted 6H-SiC

Specimens of silicon carbide (6H-SiC) were irradiated with 5 MeV Kr ions (⁸⁴Kr¹⁹⁺) for three fluences of 5×10¹³, 2×10¹⁴ and 1×10¹⁵ ions/cm², and subsequently annealed at room temperature, 500 °C, 700 °C and 1000 °C, respectively. The strain of the specimens was investigated with high resolution XRD and different defect evolution processes are revealed. An interpretation of the defect evolution and migration is given to explain the strain variation. The mechanical properties of the specimens were studied by using a nano−indentation technique in continuous stiffness measurement (CSM) mode with a diamond Berkovich indenter. For specimens irradiated with fluences of 5×10¹³ or 2×10¹⁴ ions/cm², hardness values exceed that of un−implanted SiC. However, hardness sharply degrades for specimens irradiated with the highest fluence of 1×10¹⁵ ions/cm². The specimens with fluences of 5×10¹³ and 2×10¹⁴ ions/cm² and subsequently annealed at 700 °C and 500 °C, respectively, show the maximum hardness value.