A HRXRD and nano-indentation study on Ne-implanted 6H-SiC

Specimens of 6H-SiC single crystal were irradiated at room temperature with 2.3 MeV neon ions to three successively increasing fluences of 2 x 10(14), 1.1 x 10(15) and 3.8 x 10(15) ions/cm(2) and then annealed at room temperature, 500, 700 and 1000 degrees C, respectively. The strain in the specimens was investigated with a high resolution XRD spectrometer with an omega-20 scanning. And the mechanical properties were investigated with the nano-indentation in the continuous stiffness measurement (CSM) mode with a diamond Berkovich indenter. The XRD curves of specimens after irradiation show the diffraction peaks arising at lower angles aside of the main Bragg peak Theta(Bragg), indicating that a positive strain is produced in the implanted layer. In the as-implanted specimens, the strain increases with the increase of the ion fluence or energy deposition. Recovery of the strain occurs on subsequent thermal annealing treatment and two stages of defects evolution process are displayed. An interpretation of defects migration, annihilation and evolution is given to explain the strain variations of the specimens after annealing. The nano-indentation measurements show that the hardness in as-implanted specimens first increases with the increase of the ion fluence, and a degradation of hardness occurs when the ion fluence exceeds a threshold. On the subsequent annealing, the hardness variations are regarded to be a combined effect of the covalent bonding and the pinning effect of defect clusters. (C) 2012 Elsevier B.V. All rights reserved.