High-fluence Si-implanted diamond: optimum implantation temperature for SiC formation

In this paper we investigate the effect of implantation temperature on the structural properties of diamond implanted with high fluences of Si between 5.3 ´ 1017 Si cm-2 and 1 ´ 1018 Si cm-2. In order to reduce radiation-induced damage and to enhance SiC formation the implantations were performed at elevated temperatures in the range from 900 °C to 1200 °C. Subsequently, all samples were annealed for 10 minutes at 1500 °C in an rf-heated furnace. X-ray diffraction revealed the formation of cubic SiC nanocrystallites in a buried layer inside the implanted diamond. The implantation-induced damage was assessed by analyzing graphitization of the surface-near layer using Raman spectroscopy. With increasing Si fluence the implantation-induced damage rises and the nearly perfect alignment of the formed SiC crystallites within the host diamond lattice deteriorates. However, rising the implantation temperature from 900 °C to 1000 °C reduces the damage in the diamond and increases amount, size and epitaxial alignment of the crystalline SiC precipitates. Further increase of the implantation temperature gives no improvement in the quality of the SiC rich layer. Instead, the damaged diamond converts into graphite and the formation of SiC crystallites is obstructed.