Dynamic annealing in ion implanted SiC: Flux versus temperature dependence

Abstract

A strong influence of ion implantation flux on the accumulation of radiation damage, the so-called dose rate effect, is observed and systematically studied in SiC. 100 keV Si⁺ ions were implanted into bulk 4H-SiC wafers using different ion fluxes (1.9×10¹⁰–4.9×10¹³ ions/cm² s) and keeping the implantation dose constant at 5×10¹⁴ Si⁺/cm². The implants were performed both at room and elevated temperatures, up to 220 °C. Rutherford backscattering spectrometry in the channelling mode using 2 MeV He⁺ ions was employed to measure ion implantation damage profiles in the samples. For the flux interval used the most, pronounced dynamic annealingeffect was detected at 80–160 °C, having an activation energy of 1.3 eV. For example, at 100 °C the amount of disordered Si atoms at the projected ion range is reduced by a factor of 4 by decreasing the ion flux from 4.9×10¹³ to 1.9×10¹⁰ ions/cm² s. The results are discussed in terms of migration and annihilation of intrinsic type defects for both the Si- and C-sublattices. In addition, two regions for the damage accumulation – at the surface and at the damage peak for 100 keV Si⁺ ions – are observed.