Effect of radiation damage on the migration behaviour of europium implanted into polycrystalline SiC at RT, 350 °C and 600 °C

Abstract

In this work, the effect of radiation damage on the migration behaviour of europium (Eu) implanted into polycrystalline SiC was investigated. Polycrystalline Silicon Carbide (SiC) substrates were separately implanted with europium (Eu) ions of 270 keV to a fluence of 1 × 1016 cm−2 at room temperature (RT), 350 °C and 600 °C. The samples were thermally annealed at temperatures ranging from 1000 to 1400 °C in steps of 100 °C for 5 h in vacuum. The as-implanted and annealed samples were characterized by Rutherford Backscattering Spectrometry (RBS) to monitor the depth profile of the implanted Eu, Scanning Electron Microscopy (SEM) and Raman spectroscopy to monitor surface morphology and structural changes respectively. Raman results indicated that a full amorphization was achieved in the room temperature implanted samples but not in the 350 and 600 °C implanted samples. The radiation damage gradually annealed out with increasing annealing temperature in all implanted samples; however, the full re-crystallization was not achieved up to the highest temperature. The broadening of Eu depth profile indicated some diffusion mechanism taking place in the room temperature implanted sample up to 1300 °C annealing temperature was observed. The diffusion coefficients were determined as 0.015, 0.033 and 0.035 nm2/s for samples annealed at 1000 °C, 1100 °C and 1200 °C, respectively. The 350 °C implanted sample indicated a similar form of diffusion mechanism taking place after annealing at 1000 °C, with no further peak broadening taking place at higher temperatures. A diffusion coefficient of 0.019 nm2/s was obtained at this temperature. A diffusion behaviour due to broadening after annealing at 1100 °C and higher temperatures was also observed in the 600 °C implanted sample which retained most of the implanted Eu. Due to the error limit of our RBS system, no reliable diffusion coefficients could be extracted for this sample.